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A.B. ADEBANJO 2010 COMPARISON OF CLINICAL AND IMMUNOLOGICAL RESPONSES TO ZIDOVUDINE (AZT) AND TENOFOVIR (TDF) – CONTAINING ARV REGIMENS IN PATIENTS TAKING HAART AT ROMA HEALTH SERVICE AREA OF LESOTHO. BY ADEBANJO ADEFOLARIN BABAFEMI ADEBANJO ADEFOLARIN BABAFEMI STUDENT NUMBER 15249484 Thesis submitted in partial fulfilment of the requirements for the degree M Med (Family Medicine) At Stellenbosch University August 2010 Supervisor: Dr. Michael Pather 1 A.B. ADEBANJO 2010 DECLARATION I, Adefolarin Babafemi ADEBANJO, hereby declare that the work which I hereby submit as partial fulfilment for the degree MMed (Family Medicine), on which this thesis is based, is original (except where acknowledgements indicate otherwise) and that neither the whole work nor any part of it has been submitted, or is being submitted, for another degree at this or any other university. Signed: Date: 30th August 2010 2 A.B. ADEBANJO 2010 ABSTRACT Objective: The objective of this retrospective cohort study is to assess whether demographic and anthropometric parameters, laboratory tests, co-morbidity, co-infection, treatment regimen, IRIS and adherence to treatment predict the expected response to HAART and differences if any, in the pattern of response as measured by CD4 count, weight gain and haemoglobin levels in two cohorts of patients in Roma, The Kingdom of Lesotho. Method: Data were collected randomly from a computerised database of the Antiretroviral Centre of the hospital and two cohorts of 151 subjects in each of the two arms of the study were identified from hospital records from January 2008. Each of these subjects was followed up over a period of 12 months with data obtained for at least 2 visits within the 12 month span. Data were obtained at baseline, 3 months and also at 6 and 12 months marks. Data on characteristics were compared between the two arms. Variables that may be potential confounders were identified and univariate and multivariate logistic regression analyses were carried out to establish differences independent of confounding factors for the combined endpoints as well as for each endpoint separately. Results: In all 302 patients had their records analysed and comparison of clinical and immunological response patterns in patients taking AZT and TDFcontaining ART regimens and the possible prediction of which the regimen would be better and within which population. Despite the perceived mismatch between two NRTIs it can be concluded from the results of this study that, overall, the inclusion of AZT in treatment regimen showed a modest protective effect over the TDF counterpart as measured by the endpoints of the discriminative powers of the Receiver Operating Curves of the explanatory variables being 66% 77% and 66% for CD4, Haemoglobin and Weight 3 A.B. ADEBANJO 2010 respectively, and 63% 70% and 65% for the same variables in the AZT and TDF arms of the study respectively. Conclusion: In a population of HIV patients on treatment in resource-limited settings AZT-containing regimens appear to show a slight improvement over the TDF-containing ones. 4 A.B. ADEBANJO 2010 Table of contents CHAPTER 1 ........................................................................................................................................................... 12 Study design influences ...................................................................................................................................... 23 MOTIVATION AND AIM OF THE STUDY ..................................................................................................................... 25 CHAPTER 2 ........................................................................................................................................................... 26 METHODS ................................................................................................................................................................ 26 Setting. ............................................................................................................................................................... 26 This study was conducted in a district hospital in Roma, a semi-urban region of The Kingdom of Lesotho. .... 26 Study design ....................................................................................................................................................... 26 Inclusion criteria ................................................................................................................................................ 26 Exclusion criteria ............................................................................................................................................... 26 Patient selection and sampling frame ................................................................................................................ 27 Measurement of covariates ................................................................................................................................ 27 Data analysis ..................................................................................................................................................... 28 CHAPTER 3 ........................................................................................................................................................... 30 RESULTS OF STUDY ................................................................................................................................................. 30 Conditional logistic regression analysis ............................................................................................................ 38 CHAPTER 4 ........................................................................................................................................................... 47 DISCUSSION ............................................................................................................................................................. 47 Possible limitations of the study ......................................................................................................................... 48 Bias and Confounding ........................................................................................................................................ 50 REFERENCES ............................................................................................................................................................ 53 ADDENDUM 1 .......................................................................................................................................................... 60 DATA COLLECTION FORM ........................................................................................................................................ 60 5 A.B. ADEBANJO 2010 List of tables Table 3.1 Patient demographics for the AZT cohort at baseline. Table 3.2 Patient demographics for the TDF cohort at baseline. Table 3.3 Other considerations on the AZT cohort. Table 3.4 Other considerations on the TDF cohort. Table 3.5 Univariate predictors of CD4 response at 12 months of therapy (AZT) Table 3.6 Univariate predictors of weight response at 12 months of therapy (AZT) Table 3.7 Univariate predictors of haemoglobin response at 12 months of therapy (AZT) Table 3.8 Univariate predictors of CD4 response at 12 months of therapy (TDF) Table 3.9 Univariate predictors of weight response at 12 months of therapy (TDF) Table 3.10 Univariate predictors of haemoglobin response at 12 months of therapy (TDF) Table 3.11 Adjusted Odds Ratios for retained variables for CD4 (AZT) Table 3.12 Adjusted Odds Ratios for retained variables for haemoglobin (AZT) Table 3.13 Adjusted Odds Ratios for retained variables for weight (AZT) Table 3.14 Adjusted Odds Ratios for retained variables for CD4 (TDF) Table 3.15 Adjusted Odds Ratios for retained variables for weight (TDF) Table 3.16 Adjusted Odds Ratios for retained variables for haemoglobin (TDF) 6 A.B. ADEBANJO 2010 List of figures Figure 3.1 ROC curve for AZT CD4 Figure 3.2 ROC for AZT haemoglobin Figure 3.3 ROC for AZT weight Figure 3.4 ROC for TDF CD4 Figure 3.5 ROC for TDF weight Figure 3.6 ROC for TDF haemoglobin 7 A.B. ADEBANJO 2010 Abbreviations ACTG AIDS Clinical Trial Group AIDS Acquired Immunodeficiency Syndrome ANC Antenatal Care ARV Antiretroviral AZT Zidovudine CEO Chief Executive Officer ddC Zalcitabine d4T Stavudine DNA Deoxyribonucleic Acid EDTA Ethylenediamine Tetraacetic Acid GRID Gay-Related Immune Deficiency 8 A.B. ADEBANJO 2010 HAART HIV Highly Active Antiretroviral Agents Human Immune Deficiency Virus HLTV Human T-Lymphotrophic Virus IRIS Immune Reconstitution Inflammatory Syndrome LAV Lymphadenopathy-Associated Virus MTCT Mother-To-Child Transmission NGO Non-Governmental Organization NNRTI Non-Nucleoside Reverse Transcriptase Inhibitor NRTI Nucleoside Reverse Transcriptase Inhibitor OIP Opportunistic Infection Prophylaxis PCP Pneumocystis Pneumonia PHC Primary Health Care 9 A.B. ADEBANJO 2010 PMTCT Prevention of Mother-To-Child Transmission RNA Ribonucleic Acid TDF Tenofovir UNAIDS United Nations Programme on HIV/AIDS VCT Voluntary Counselling and Testing WHO World Health Organization 10 A.B. ADEBANJO 2010 CHAPTER 1 Background The burden that the HIV/AIDS pandemic has put on economies of countries particularly on the developing countries in sub-Saharan Africa as well as on infected and affected people necessitated the development of various interventions of which antiretroviral agents are principal. Worst hit countries of the world are still grappling with effective coverage of their various sub regions and have developed several programs to scale up the supply of antiretroviral agents, manage complications effectively and train various staff to perform these functions. However, it is not just enough to have indiscriminate roll-out of these agents to eligible individuals and have efforts made at ensuring proper adherence and adequate follow-up. Needless to say, similar efforts are needed to predict the possible outcomes of therapy prior to its commencement in eligible individuals, to determine the factors that drive response in some patients while similar responses are not seen in others. This will tend to improve overall outcome of patients placed on antiretroviral agents. This study will look at an HIV cohort in a district hospital in Roma, a semiurban region of Lesotho. 11 A.B. ADEBANJO 2010 Literature Review INTRODUCTION Human immunodeficiency virus (HIV) is a retrovirus that causes acquired immunodeficiency syndrome (AIDS), a condition in humans in which the immune system begins to fail, leading to life-threatening opportunistic infections. Previous names for the virus include human T-lymphotropic virusIII (HTLV-III), lymphadenopathy-associated virus (LAV), or AIDS-associated retrovirus (ARV).[1,2] Infection with HIV occurs by the transfer of blood, semen, vaginal fluid, preejaculate, or breast milk. Within these bodily fluids, HIV is present as both free virus particles and virus within infected immune cells. The three major routes of transmission are unprotected sexual intercourse, contaminated needles, and transmission from an infected mother to her baby during pregnancy or at birth, or through breast milk. Screening of blood products for HIV in the developed world has largely eliminated transmission through blood transfusions or infected blood products in these countries. HIV infection in humans is now pandemic in certain geographic areas . As of January 2006, the Joint United Nations Programme on HIV/AIDS (UNAIDS) and the World Health Organization (WHO) estimate that AIDS has killed more than 25 million people since it was first recognized on December 1, 1981, making it one of the most destructive pandemics in recorded history. In 2005 alone, AIDS claimed an estimated 2.4–3.3 million lives, of which more than 570,000 were children. It is estimated that about 0.6% of the world's living population is infected with HIV.[3] A third of these deaths are occurring in subSaharanAfrica, retarding economic growth and increasing poverty.[4] According to current estimates, HIV is set to infect 90 million people in Africa, resulting in 12 A.B. ADEBANJO 2010 a minimum estimate of 18 million orphans.[5] Antiretroviral treatment reduces both the mortality and the morbidity of HIV infection, but routine access to antiretroviral medication is not available in all countries.[6] HIV primarily infects vital cells in the human immune system such as helper T cells (specifically CD4+ T cells), macrophages and dendritic cells. HIV infection leads to low levels of CD4+ T cells through three main mechanisms: firstly, direct viral destruction of infected cells; secondly, increased rates of apoptosis in infected cells; and thirdly, killing of infected CD4+ T cells by CD8 cytotoxic lymphocytes that recognize infected cells. When CD4+ T cell numbers decline below a critical level, cell-mediated immunity is lost, and the body becomes progressively more susceptible to opportunistic infections. If untreated, eventually most HIV-infected individuals develop AIDS (Acquired Immunodeficiency Syndrome) and die; however about one in ten remains healthy for many years, with no noticeable symptoms.[7] Treatment with antiretrovirals, where available, increases the life expectancy of people infected with HIV. It is hoped that current and future treatments may allow HIVinfected individuals to achieve a life expectancy approaching that of the general public. ORIGIN AND DISCOVERY The AIDS epidemic officially began on June 5, 1981, when the U.S. Centers for Disease Control and Prevention reported a cluster of Pneumocystis pneumonia (PCP) caused by a form of Pneumocystis carinii, now recognized as a distinct species Pneumocystis jirovecii, in five homosexual men in Los Angeles.[8] The disease was originally dubbed GRID, or Gay-Related Immune Deficiency, but health authorities soon realized that nearly half of the people identified with the syndrome were not homosexual men. In 1982, the CDC introduced the 13 A.B. ADEBANJO 2010 term AIDS to describe the newly recognized syndrome, though it was still casually referred to as GRID. In 1983, scientists led by Luc Montagnier at the Pasteur Institute in France first discovered the virus that causes AIDS.[9] They called it lymphadenopathyassociated virus (LAV). A year later a team led by Robert Gallo of the United States confirmed the discovery of the virus, but they renamed it human T lymphotropic virus type III (HTLV-III).[10] The dual discovery led to considerable scientific disagreement, and it was not until President Mitterrand of France and President Reagan of the USA met that the major issues were resolved. In 1986, both the French and the U.S. names for the virus itself were dropped in favour of the new term, human immunodeficiency virus (HIV).[2] HIV was classified as a member of the genus Lentivirus,[11] part of the family of Retroviridae.[12] Lentiviruses have many common morphologies and biological properties. Many species are infected by lentiviruses, which are characteristically responsible for long-duration illnesses with a long incubation period.[13] Lentiviruses are transmitted as single-stranded, positive-sense, enveloped RNA viruses. Upon entry of the target cell, the viral RNA genome is converted to double-stranded DNA by a virally encoded reverse transcriptase that is present in the virus particle. This viral DNA is then integrated into the cellular DNA by a virally encoded integrase so that the genome can be transcribed. Once the virus has infected the cell, two pathways are possible: either the virus becomes latent and the infected cell continues to function, or the virus becomes active and replicates, and a large number of virus particles are liberated that can then infect other cells. Two species of HIV infect humans: HIV-1 and HIV-2. HIV-1 is thought to have originated in southern Cameroon after jumping from wild chimpanzees (Pan troglodytes troglodytes) to humans during the twentieth century.[14][15] HIV-2 may have originated from the Sooty Mangabey (Cercocebus atys), an Old World 14 A.B. ADEBANJO 2010 monkey of Guinea-Bissau, Gabon, and Cameroon.[16] HIV-1 is more virulent. It is easily transmitted and is the cause of the majority of HIV infections globally. HIV-2 is less transmittable and is largely confined to West Africa.[16] HIV-1 is the virus that was initially discovered and termed LAV. Three of the earliest known instances of HIV-1 infection are as follows: A plasma sample taken in 1959 from an adult male living in what is now the Democratic Republic of Congo.[17] HIV found in tissue samples from a 15-year-old African-American teenager who died in St. Louis in 1969.[18] HIV found in tissue samples from a Norwegian sailor who died around 1976.[19] Although a variety of theories exist explaining the transfer of HIV to humans, no single hypothesis is unanimously accepted, and the topic remains controversial. The most widely accepted theory is so called 'Hunter' Theory according to which transference from simian to human most likely occurred when a human was bitten by a monkey or was cut while butchering one, and the human became infected.[20] The Times published an article in 1987 stating that WHO suspected some kind of connection with its vaccine program and AIDS-epidemic. The story was almost entirely based on statements given by one unnamed WHO advisor. The theory was supported only by weak circumstantial evidence and is now disproven by unraveling the genetic code of the virus and finding out that the virus dates back to the 1930s.[21] Freelance journalist Tom Curtis discussed one controversial possibility for the origin of HIV/AIDS in a 1992 Rolling Stone magazine article. He put forward what is now known as the OPV AIDS hypothesis, which suggests that AIDS was inadvertently caused in the late 1950s in the Belgian Congo by Hilary 15 A.B. ADEBANJO 2010 Koprowski's research into a polio vaccine.[22] Although subsequently retracted due to libel issues surrounding its claims, the Rolling Stone article motivated another freelance journalist, Edward Hooper, to probe more deeply into this subject. Hooper's research resulted in his publishing a 1999 book, The River, in which he alleged that an experimental oral polio vaccine prepared using chimpanzee kidney tissue was the route through which simian immunodeficiency virus (SIV) crossed into humans to become HIV, thus starting the human AIDS pandemic.[23] This theory is contradicted by an analysis of genetic mutation in primate lentivirus strains that estimates the origin of the HIV-1 strain to be around 1930, with 95% certainty of it lying between 1910 and 1950.[24] EPIDEMIOLOGY UNAIDS and the WHO estimate that AIDS has killed more than 25 million people since it was first recognized in 1981, making it one of the most destructive pandemics in recorded history. Despite recent improved access to antiretroviral treatment and care in many regions of the world, the AIDS pandemic claimed an estimated 2.8 million (between 2.4 and 3.3 million) lives in 2005 of which more than half a million (570,000) were children.[3] Globally, between 33.4 and 46 million people currently live with HIV.[3] In 2005, between 3.4 and 6.2 million people were newly infected and between 2.4 and 3.3 million people with AIDS died, an increase from 2004 and the highest number since 1981. Sub-Saharan Africa remains by far the worst-affected region, with an estimated 21.6 to 27.4 million people currently living with HIV. Two million [1.5– 3.0 million] of them are children younger than 15 years of age. More than 64% 16 A.B. ADEBANJO 2010 of all people living with HIV are in sub-Saharan Africa, as are more than three quarters of all women living with HIV. In 2005, there were 12.0 million [10.6– 13.6 million] AIDS orphans living in sub-Saharan Africa.[3] South & South East Asia are second-worst affected with 15% of the total. AIDS accounts for the deaths of 500,000 children in this region. Two-thirds of HIV/AIDS infections in Asia occur in India, with an estimated 5.7 million infections (estimated 3.4– 9.4 million) (0.9% of population), surpassing South Africa's estimated 5.5 million (4.9–6.1 million) (11.9% of population) infections, making India the country with the highest number of HIV infections in the world.[25] In the 35 African nations with the highest prevalence, average life expectancy is 48.3 years—6.5 years less than it would be without the disease.[26] The latest evaluation report of the World Bank's Operations Evaluation Department assesses the development effectiveness of the World Bank's country-level HIV/AIDS assistance defined as policy dialogue, analytic work, and lending with the explicit objective of reducing the scope or impact of the AIDS epidemic.[27] This is the first comprehensive evaluation of the World Bank's HIV/AIDS support to countries, from the beginning of the epidemic through mid-2004. Because the Bank aims to assist in implementation of national government programmes, their experience provides important insights on how national AIDS programmes can be made more effective. The development of Highly Active Antiretroviral Therapy (HAART) as effective therapy for HIV infection and AIDS has substantially reduced the death rate from this disease in those areas where these drugs are widely available. This has created the misperception that the disease has vanished. In fact, as the life expectancy of persons with AIDS has increased in countries where HAART is widely used, the number of persons living with AIDS has increased substantially. In the United States, the number of persons with AIDS increased from about 35,000 in 1988 to over 220,000 in 1996.[28] 17 A.B. ADEBANJO 2010 In Africa, the number of Mother-To-Child Transmission (MTCT) and the prevalence of AIDS is beginning to reverse decades of steady progress in child survival. Countries such as Uganda are attempting to curb the MTCT epidemic by offering VCT (voluntary counselling and testing), PMTCT (prevention of mother-to-child transmission) and ANC (ante-natal care) services, which include the distribution of antiretroviral therapy. TREATMENT There is currently no vaccine or cure for HIV or AIDS. The only known method of prevention is avoiding exposure to the virus. However, an antiretroviral treatment, known as post-exposure prophylaxis is believed to reduce the risk of infection if begun directly after exposure.[29] Current treatment for HIV infection consists of HAART.[30] This has been highly beneficial to many HIV-infected individuals since its introduction in 1996, when the protease inhibitor-based HAART initially became available.[31] Current HAART options are combinations (or "cocktails") consisting of at least three drugs belonging to at least two types, or "classes," of anti-retroviral agents. Typically, these classes are two nucleoside analogue reverse transcriptase inhibitors (NARTIs or NRTIs) plus either a protease inhibitor or a non-nucleoside reverse transcriptase inhibitor (NNRTI). Because AIDS progression in children is more rapid and less predictable than in adults, particularly in young infants, more aggressive treatment is recommended for children than adults.[32] In developed countries where HAART is available, doctors assess their patients thoroughly: measuring the viral load, how fast CD4 declines, and patient readiness. They then decide when to recommend starting treatment.[33] 18 A.B. ADEBANJO 2010 MONITORING TREATMENT HAART allows the stabilization of the patient’s symptoms and the suppression of viraemia, but it does cure the patient, and high levels of HIV-1, often HAART resistant, return once treatment is stopped.[34,35] Moreover, it would take more than a lifetime for HIV infection to be cleared using HAART.[36] Despite this, many HIV-infected individuals have experienced remarkable improvements in their general health and quality of life, which has led to a large reduction in HIV-associated morbidity and mortality in the developed world.[31,37,38] A computer based study in 2006 projected that following the 2004 United States treatment guidelines gave an average life expectancy of an HIV infected individual to be 32.1 years from the time of infection if treatment was started when the CD4 count was 350/µL.[39] This study was limited as it did not take into account possible future treatments and the projection has not been confirmed within a clinical cohort setting. In the absence of HAART, progression from HIV infection to AIDS has been observed to occur at a median of between nine to ten years and the median survival time after developing AIDS is only 9.2 months.[40] However, HAART sometimes achieves far less than optimal results, in some circumstances being effective in less than fifty percent of patients. This is due to a variety of reasons such as medication intolerance/side effects, prior ineffective antiretroviral therapy and infection with a drug-resistant strain of HIV. However, non-adherence and nonpersistence with antiretroviral therapy is the major reason most individuals fail to benefit from HAART.[41] The reasons for non-adherence and non-persistence with HAART are varied and overlapping. Major psychosocial issues, such as poor access to medical care, inadequate social supports, psychiatric disease and drug abuse contribute to non-adherence. The complexity of these HAART regimens, whether due to pill number, dosing frequency, meal restrictions or other issues along with side effects that create intentional non-adherence also contribute to this problem.[42,43,44] The side effects include lipodystrophy, 19 A.B. ADEBANJO 2010 dyslipidaemia, insulin resistance, an increase in cardiovascular risks and birth defects.[45,46] The timing for starting HIV treatment is still debated. There is no question that treatment should be started before the patient's CD4 count falls below 200, and most national guidelines say to start treatment once the CD4 count falls below 350; but there is some evidence from cohort studies that treatment should be started before the CD4 count falls below 350.[47,37] There is also evidence to say that treatment should be started before CD4 percentage falls below 15%.[48] In those countries where CD4 counts are not available, patients with WHO stage III or IV disease[49] should be offered treatment. Anti-retroviral drugs are expensive, and the majority of the world's infected individuals do not have access to medications and treatments for HIV and AIDS.[50] Research to improve current treatments includes decreasing side effects of current drugs, further simplifying drug regimens to improve adherence, and determining the best sequence of regimens to manage drug resistance. Unfortunately, only a vaccine is thought to be able to halt the pandemic. This is because a vaccine would cost less, thus being affordable for developing countries, and would not require daily treatment.[50] However, after over 20 years of research, HIV-1 remains a difficult target for a vaccine.[50] In February 2007, The National Institute of Allergy and Infectious Diseases published a report that gave details of a potential region on HIV's surface that is a potential target for a vaccine.[51] 20 A.B. ADEBANJO 2010 PREDICTING RESPONSE TO TREATMENT The ability to use clinical or laboratory findings to predict antiretroviral success or failure is a singular most vital component of HIV care and management. Two developments have spurred on this field of research. The first is the "death" of the large clinical endpoint trial. The second is the advances in developing surrogate markers of response. The definition of antiretroviral response is usually based upon clinical endpoints (i.e., infections, death, and quality-of-life) or surrogate markers (i.e., predictors of the clinical endpoints). For years we have used CD4+ lymphocyte counts -- host-related factors -- as a surrogate marker. More recently, HIV-1 RNA tissue and serum levels have been employed as surrogate markers. Currently, many new markers related to the host, the virus, or the drugs are being evaluated for correlation between clinical status and progress, and response to therapy. A session at this conference titled, "Predictors of Response to Antiretroviral Therapy," highlighted some of the research currently underway. David Katzenstein, of Stanford University reviewed the predictive markers of clinical endpoints in a nested case-cohort study of AIDS Clinical Trials Group (ACTG)-175 (abstract 12124). This was a trial of zidovudine versus zidovudine plus ddI versus zidovudine plus zalcitabine (ddC) versus ddI in asymptomatic patients with CD4+ lymphocyte counts of between 200 to 500 cells/cu mm. Comparison of 245 patients who progressed (ie, experienced either an AIDSdefining illness or death) versus 212 controls showed that both CD4+ lymphocyte count and HIV-1 RNA levels at week eight were predictive of outcome. 21 A.B. ADEBANJO 2010 For example, there was a 74% reduction in risk of progression in those who had a 1 log decline in serum HIV-1 RNA levels after eight weeks of therapy. The researchers were able to create a table, which predicted outcomes. For example, 95% of those who had a CD4+ count > 300 cells/cu mm and a serum HIV-1 RNA level < 1,000 were AIDS-free after 30 months. In contrast, no patient with a week eight serum HIV-1 RNA level > 10,000 and a CD4+ lymphocyte count < 200 cells/cu mm remained AIDS-free. Katzenstein emphasized that HIV-1 RNA levels remained predictive at each year of measurement. His surprising suggested application of this trend was that more aggressive therapy may be delayed in persons with a CD4+ lymphocyte count > 200 cells/cu mm and an HIV-1 RNA < 10,000 copies/mL. This is in contrast to what many experts recommend: that the very first regimen should be designed to maximize suppression of HIV-1 replication in order to circumvent the development of mutations which may lessen the benefit of antiretroviral therapy in the future. MEASURING RESPONSE Regular monitoring of the CD4 count and viral load is critical to identify poor adherence to therapy or treatment failure early. The CD4 count should be performed every 3-6 months. The viral load should be done 6-8 weeks after commencing antiretroviral therapy and then every 3-6 months together with the CD4 count. The purpose of early viral load test is to detect an adequate viral load response (more than 1 log reduction). These tests should not be done following vaccination or if an intercurrent infection is present, as this will transiently increase the viral load and give a falsely low value of the CD4 count. 22 A.B. ADEBANJO 2010 With HAART, at least a ten-fold (1 log) drop in the viral load can be expected within 8 weeks and the viral load should be undetectable after 16-24 weeks of therapy. The viral load is the most important test for monitoring response to therapy. [52] The CD4 count rises rapidly within 4 weeks on starting HAART and then more gradually. The average rise in CD4 is about 75 in the first 6 months, 150 in the first year and 80 per annum thereafter, but this is extremely variable. In some patients (about 10-20%) the CD4 fails to rise despite a suppressed viral load there is no point in changing their HAART regimens. [52] Clinical monitoring is also important, including general well-being and sustained weight gain. Changes to therapy should not be based only on laboratory results. It is important to note that an intercurrent clinical event should not be an indication for changing therapy if the viral load is suppressed. Furthermore, clinical deterioration and CD4 decline both occur after many months of virological failure, thus the main criterion for changing initial HAART regimen is virological failure. Study design influences Case definition of response Regensberg and Whitelaw [2007] examined the trend and patterns in the viral load at 8, 16 and 24 weeks of therapy and their findings influence the defining of clinical, virological and immunological case response with differing extents. According to the authors, there appears to be no gold standard for the definition of response, and studies have reported widely varying degrees [52]. 23 A.B. ADEBANJO 2010 Bias and confounding Selection bias is a systematic error that may occur in studies where subjects are selected by using a procedure or by factors that may influence the participation in a study [53]. This type of bias comes about when the association between exposure and disease differs between those who participate and those who do not participate in the study. However, the use of computer-generated case file numbers to select participants into the study and incorporating this in the study design reduces to a large extent selection bias due to the inappropriate selection of cases. The misclassification of subjects can lead to information bias if the information collected from study subjects is erroneous [53]. When using a categorical scale, a person may be placed in the incorrect category or misclassified as a result of this error. Study design choice In the absence of randomised controlled trials (RCTs) with clinical endpoints relevant to the individual patient, to evaluate response and the pattern of differences of HAART non-experimental studies have been applied. Prospective and retrospective cohort studies have been used as well as case-control designs. Of these, the prospective cohort study has consistently been regarded as the strongest design [53]. Retrospective studies are usually more economical, especially when medical records have to be reviewed to retrieve valid information on large numbers of people. By using this study design, one can assess the effectiveness of HAART on endpoints such as changes in CD4 pattern weight and haemoglobin. Lower costs and enhanced timelines are some of the advantages of retrospective studies over RCTs [53]. 24 A.B. ADEBANJO 2010 Motivation and aim of the study Antiretroviral therapy is available for free in most parts of Lesotho and all government-owned as well as religious institutions of health provide HIV allied services such as counselling and support, health education, laboratory investigations and treatment of opportunistic infections for free. Despite all these measures however, not all patients respond equally to antiretroviral agents and it is the thinking of most lay people and especially HIV-infected persons that once antiretroviral agents have been commenced then a patient is on his way to full recovery. Unfortunately, health workers in the field of HIV/AIDS who sometimes inappropriately initiate patients on treatment sometimes echo this sentiment. Despite good measures of community based motivation and extensive education on the concept of antiretroviral agents, there still remains that erroneous impression that whatever time a patient is started on therapy and regardless of duration or extent of illness, the patient was bound to recover fully. We want to know who will respond and who wouldn't. In addition this type of study has never been done in this part of the country. Aim: To study the response pattern and the differences in response to antiretrovirals in the 2 cohorts over a 12 month period. Objectives: To assess whether anthropometric parameters, laboratory tests, co-morbidity or co-infection with opportunistic agents, treatment regimen, IRIS and adherence predict response to HAART as measured by CD4 count, weight gain and functional status over a time period of one year. 25 A.B. ADEBANJO 2010 CHAPTER 2 Methods Setting. This study was conducted in a district hospital in Roma, a semi-urban region of The Kingdom of Lesotho. Study design The study design employed for this study is the Retrospective Cohort Study Design. Data were collected from a cohort of patients with at least 12 months follow up and with at least 2 visits in the 12 months. The cohort was started when the patients were put on ART and follow up for at least 12 months starting January 2008. Inclusion criteria Must be HIV positive Must be on antiretroviral therapy Must have had a CD 4 count of 200 cells or less at initiation of treatment Must have been on treatment for at least 12 months and have at least 2 clinic visits during the study period Exclusion criteria Patients with CD 4 count of > 200 cells Patients not initiated on treatment within the study period Defaulters of treatment (did not participate in treatment for at least 6 months). 26 A.B. ADEBANJO 2010 Patient selection and sampling frame Sample of patients consists of a cohort of 302 adult subjects initiated on antiretroviral therapy from January 2008. Subjects in this study are essentially cases detected in the out-patient department, those detected on in-patient basis and those identified during routine community-based screening exercises. The subjects selected for the study were divided into two arms each representing a separate group of the study based on the HAART regimen they were placed. Identification of cases Subjects in the cohorts qualified as cases if they were eligible and already started on HAART as at the time the study began and continued on treatment regardless of hospital admission or therapy for co-morbidities during the period from January 2008 to January 2009 as confirmed by hospital (PHC)claims data. Patients were identified as defaulters of treatment if they did not have at least two follow up visits during the course of this study and were not eligible to become cases. Also excluded from the study were patients who were lost to follow up. The ART center database was used to identify patients who died or defaulted during this period. Measurement of covariates The following data was retrieved from the membership, authorisation for medicine and hospitalisation claims databases for each of the cases: 27 A.B. ADEBANJO 2010 Demographic covariates Age (measured on the 1st of January 2008 in years) Gender (male or female) Covariates indicating opportunistic infections conditions These covariate data regarded as input variables for the purposes of this study were determined from chronic medication authorisations and database and are non-mutually exclusive (0 = condition not registered; 1 = condition registered). Covariates related to therapy This refers to the treatment modality adopted for each subject. The outcomes of interest are a direct function of the member of the NRTI group of antiretroviral therapy included in the patient's medication. Data management All patient data was captured on form designed on Microsoft Access and this program was subsequently used to produce a data spreadsheet on Microsoft Excel where all data cleansing and editing were done. Thereafter data was transferred to STATA version 10 statistical computer package via STATTRANSFER version 7, for analysis. Data analysis Stata 10 software was used to perform the data analysis [54]. The controls were compared in terms of exposure status, and the variables where a significant difference was shown were eligible to be used in the models as potential confounders if they also differed significantly between cases and controls. 28 A.B. ADEBANJO 2010 Baseline characteristics were analysed using chi-square tests for categorical and continuous variables. Explanatory models utilizing univariate regression analyses were used to determine the influence of the different variables on the odds ratios estimating response. Multivariate logistic regression analysis was used to assess therapy effectiveness independent of confounding factors for the combined endpoint. To assess the fit of the models, post-estimation statistics in STATA 10 software were used [54]. Finally, HAART effectiveness and differences between the groups were calculated as 1-(odds ratio) as determined by the logistic regression models. 29 A.B. ADEBANJO 2010 CHAPTER 3 Results of Study The results of this study will be reported in the following sequence. Patient selection Demographic characteristics Outcome measures in the following order; CD4 count, Weight response and finally Haemoglobin. The reporting of the outcome measures will essentially be done at baseline and then at 12 months Logistic regression modeling was used to explore the relationship between Sex, Age, TB history, ART regimen and Opportunistic infection history (all being explanatory variables) and CD4 count, Weight estimation and changes in Haemoglobin concentration (being the outcome variables) at one year. Stepwise backward binary logistic regression was carried out using STATA version 10. Sex, TB history and Opportunistic infection history were modeled as dichotomous variables. The variable Age was modeled first as a continuous variable and then as a categorical variable with three categories corresponding to the terciles for the ages. The specification for age was then selected that gave the best goodness of fit characteristics. Variables were dropped from the model only if the LR test was statistically significant. The Pearson’s goodness of fit test was carried out post regression and the area under the receiver operating characteristic (ROC) curve was calculated as well. 30 A.B. ADEBANJO 2010 PATIENT SELECTION INTO BOTH ARMS OF STUDY Of the patients that went through the mandatory pre-HAART evaluation leading to successful work up for HAART, 302 of them were randomly selected from the computerized patient database to prevent selection bias and as mentioned earlier, patients who died or did not have up to a minimum two clinic visits during the review period were excluded from the study. Patient enrollment Patients randomly selected into the AZT arm 151 Patients randomly selected into the TDF arm 151 Patients who died during the review period 14* Patients that did not have at least 2 follow up visits 9** *Excluded from study **Excluded and replaced in study PATIENT DEMOGRAPHICS At baseline there were no statistically significant differences between the two arm of study with regards to patient demographics. (Tables 3.1 and 3.2) Table 3.1: Patient demographics for the AZT cohort at baseline Parameter Mean (SD) CD4 count 108.54 (52.71) Haemoglobin 11.54 (1.79) Weight 55.62 (11.96) Median 112 11.5 54 Age 38.97 (12.16) 31 A.B. ADEBANJO 2010 Table 3.2: Patient demographics for the TDF cohort at baseline Parameter Mean (SD) Median CD4 count 117.40 (52.40) 121 Haemoglobin 11.98 (4.42) Weight 53.92 (10.38) 11.6 54 Age 37.61 (12.36) Table 3.3 Other considerations on the AZT cohort Parameter n Gender: Female TB history Treatment 3: AZT+3TC+EFV Treatment 4: AZT+3TC+NVP Measurement n (%) 151 (100) 110 (72.85) 37 (24.5) 69 (45.70) 82 (54.30) Table 3.4 Other considerations on the TDF cohort Parameter n Gender: Female TB history Treatment 2: TDF+3TC+EFV Treatment 1: TDF+3TC+NVP Measurement n (%) 151 (100) 94 (62.25) 62 (41.06) 124 (82.12) 27 (17.88) Treatment: All patients were placed on treatment in accordance to the national ART guidelines which stipulates triple therapy. All patients in both arms of the study had two NRTIs and one NNRTI. Representation by TDF 3TC and EFV was highest (124) and 82 percent of subjects on the TDF arm of the study, followed by AZT 3TC and NVP with 82 subjects representing 54 percent of patients on the AZT arm of the study followed by AZT 3TC and EFV with 69 subjects (45.7%), and TDF 3TC and NVP with 27 subjects (18%), respresenting the AZT and TDF arms respectively. 32 A.B. ADEBANJO 2010 Age: The age in the two groups were normally distributed, and the means and standard deviations did not differ significantly (tables 3.1 and 3.2). (p = 0.05) Gender: The majority of patients in both groups were female (tables 3.3 and 3.4). The Chi2 test confirms that the proportion of Male to Female in the two groups does not differ significantly. THE AZT ARM OF STUDY The purpose of performing a univariate analysis in this study was to establish if at the end of review period there was any statistically significant differences between variables and to identify potential confounding factors that may influence the results. Firstly, it was established which variables varied significantly across the review period in this study. Tables 3.5, 3.6 and 3.7 describe the univariate analyses in terms of the AZT arm of the study during the review period. Variables with a statistically significant difference (p-value ≤ 0.05) could have been potential confounders in a statistical model if they were also associated with the outcomes of interest. TABLE 3.5: TABLE OF UNIVARIATE PREDICTORS OF CD4 RESPONSE AT 12 MONTHS OF THERAPY Variable sex tbhistory n Description (explanation) 151 (males=41) 151 Participant’s gender History of TB Odds Ratio CD4 RESPONSE AT 12 MONTHS OF THERAPY Log Likelihood Chi2 Prob 95% CI 0.37 -98.72 7.03 0.008 0.18-0.78 0.77 -101.99 0.48 0.488 0.36-1.62 33 A.B. ADEBANJO 2010 oihistory age art regimen TABLE (present=37) 150 (present=65) 151 (3 centiles) 0-28 years 28-35 years 35-44 years 44-100 years 151 (2 groups) artreg 3 artreg 4 History of opportunistic infections Participant’s age in groups group 1 group 2 group 3 group 4 1.66 -100.23 2.23 0.136 0.85-3.23 Referent 0.57 1.72 0.77 Referent -101.18 -101.28 -101.99 Referent 2.12 1.93 0.48 Referent 0.145 0.165 0.488 Referent AZT+3TC+NVP Referent AZT+3TC+EFV 0.66 Referent -101.47 Referent 1.55 Referent 0.214 Referent 0.27-1.21 0.79-3.74 0.36-1.62 0.34-1.27 3.6: TABLE OF UNIVARIATE PREDICTORS OF WEIGHT RESPONSE AT 12 MONTHS OF THERAPY Variable sex tbhistory oihistory age art n Description (explanation) 151 (males=41) 151 (present=37) 150 (present=65) 151 (3 centiles) 0-28 years 28-35 years 35-44 years 44-100 years 151 Odds Ratio WEIGHT RESPONSE AT 12 MONTHS OF THERAPY Log Likelihood Chi2 Prob 95% CI Participant’s gender History of TB 0.42 -101.91 5.50 0.019 0.20-0.88 1.96 -103.12 3.08 0.079 0.92-4.19 History of opportunistic infections Participant’s age in groups group 1 group 2 group 3 group 4 0.95 -103.96 0.03 0.869 0.50-1.81 Referent 0.02 0.00 0.99 Referent 0.886 0.962 0.321 Referent Referent 0.95 1.02 1.46 Referent -104.65 -104.66 -104.17 0.45-1.99 0.49-2.12 0.69-3.08 34 A.B. ADEBANJO 2010 regimen TABLE (2 groups) artreg 3 artreg 4 AZT+3TC+NVP Referent AZT+3TC+EFV 0.79 Referent -104.40 Referent 0.53 Referent 0.466 Referent 0.42-1.50 3.7: TABLE OF UNIVARIATE PREDICTORS OF HAEMOGLOBIN RESPONSE AT 12 MONTHS OF THERAPY Variable sex tbhistory oihistory age art regimen n Description (explanation) 151 (males=41) 151 (present=37) 150 (present=65) 151 (3 centiles) 0-28 years 28-35 years 35-44 years 44-100 years 151 (2 groups) artreg 3 artreg 4 Odds Ratio HB RESPONSE AT 12 MONTHS OF THERAPY Log Likelihood Chi2 Prob 95% CI Participant’s gender History of TB 4.04 -82.04 12.53 0.0004 1.86-8.76 1.41 -87.96 0.67 0.413 0.63-3.15 History of opportunistic infections Participant’s age in groups group 1 group 2 group 3 group 4 0.68 -87.45 1.06 0.304 0.33-1.43 Referent 1.41 0.65 0.44 Referent -87.96 -87.80 -86.70 Referent 0.67 0.99 3.19 Referent 0.413 0.320 0.074 Referent AZT+3TC+NVP Referent AZT+3TC+EFV 0.44 Referent -85.88 Referent 4.85 Referent 0.028 Referent 0.63-3.15 0.27-1.56 0.17-1.14 0.21-0.92 35 A.B. ADEBANJO 2010 THE TDF ARM OF STUDY At one year of treatment both arms of the study appeared similar and no statistically significant differences between the groups (Table 3.8, 3.9 and 3.10). TABLE 3.8: TABLE OF UNIVARIATE PREDICTORS OF CD4 RESPONSE AT 12 MONTHS OF THERAPY Variable n Description (explanation) sex 151 (males=57) 151 (present=62) 151 (present=60) tbhistory oihistory age art regimen 151 (3 centiles) 0-29 years 29-37 years 37-45 years 45-100 years 151 (2 groups) artreg 1 artreg 2 Odds Ratio CD4 RESPONSE AT 12 MONTHS OF THERAPY Log Likelihood Chi2 Prob 95% CI Participant’s gender History of TB 0.87 -95.80 0.16 0.689 0.43-1.74 1.07 -95.86 0.03 0.852 0.54-2.13 History of opportunistic infections Participant’s age in groups group 1 group 2 group 3 group 4 1.64 -94.93 1.90 0.169 0.80-3.35 Referent 1.47 1.50 0.49 Referent -95.39 -95.43 -94.30 Referent 0.98 0.90 3.16 Referent 0.323 0.343 0.075 Referent TDF+3TC+NVP Referent TDF+3TC+EFV 0.40 Referent -94.16 Referent 3.43 Referent 0.064 Referent 0.68-3.18 0.64-3.51 0.23-1.07 0.14-1.13 36 A.B. ADEBANJO 2010 TABLE 3.9: TABLE OF UNIVARIATE PREDICTORS OF WEIGHT RESPONSE AT 12 MONTHS OF THERAPY Variable n Description (explanation) sex 151 (males=57) 151 (present=62) 151 (present=60) tbhistory oihistory age art regimen 151 (3 centiles) 0-29 years 29-37 years 37-45 years 45-100 years 151 (2 groups) artreg 1 artreg 2 Odds Ratio WEIGHT RESPONSE AT 12 MONTHS OF THERAPY Log Likelihood Chi2 Prob 95% CI Participant’s gender History of TB 0.34 -91.75 8.27 0.004 0.16-0.73 1.53 -95.14 1.48 0.224 0.77-3.04 History of opportunistic infections Participant’s age in groups group 1 group 2 group 3 group 4 1.89 -94.25 3.26 0.071 0.95-3.76 Referent 0.92 1.13 0.90 Referent -95.86 -95.83 -95.85 Referent 0.05 0.09 0.06 Referent 0.828 0.760 0.809 Referent TDF+3TC+NVP Referent TDF+3TC+EFV 0.81 Referent -95.77 Referent 0.23 Referent 0.635 Referent 0.43-1.95 0.51-2.53 0.40-2.04 0.34-1.93 37 A.B. ADEBANJO 2010 TABLE 3.10: TABLE OF UNIVARIATE PREDICTORS OF HAEMOGLOBIN RESPONSE AT 12 MONTHS OF THERAPY Variable n Description (explanation) sex 151 (males=57) 151 (present=62) 151 (present=60) tbhistory oihistory age art regimen 151 (3 centiles) 0-29 years 29-37 years 37-45 years 45-100 years 151 (2 groups) artreg 1 artreg 2 Odds Ratio HB RESPONSE AT 12 MONTHS OF THERAPY Log Likelihood Chi2 Prob 95% CI Participant’s gender History of TB 2.30 -84.83 4.94 0.062 1.10-4.81 1.25 -87.12 0.35 0.556 0.60-2.58 History of opportunistic infections Participant’s age in groups group 1 group 2 group 3 group 4 1.17 -87.21 0.17 0.678 0.56-2.44 Referent 0.63 1.45 0.95 Referent -86.70 -86.92 -87.29 Referent 1.20 0.75 0.01 Referent 0.273 0.386 0.905 Referent TDF+3TC+NVP Referent TDF+3TC+EFV 5.52 Referent -83.54 Referent 7.51 Referent 0.006 Referent 0.27-1.47 0.63-3.34 0.40-2.25 1.24-24.5 Conditional logistic regression analysis The unadjusted odds ratio at 12 months in both arms of the study for CD4 response showed similar pattern with the exception of history of Opportunistic Infections which appeared to suggest a modest increased risk with respect therapy with TDF-containing ART regimen 1.64 [95% CI, 0.80 - 3.35]. There was no difference in the pattern of response with the variable haemoglobin as 38 A.B. ADEBANJO 2010 the male gender responded significantly much less than the female gender. Odds ratio 4.04 and 2.30 [95% CI, 1.86 - 8.76 and 1.10 - 4.81] for the AZT and TDF arms respectively. Then the variables that differed between the AZT and the TDF arms were entered into each model one at a time. Variables that were not statistically significantly different (p-value ≤ 0.05) between cases and controls were not entered into the explanatory model. After entering demographic variables, i.e. age and gender, the variables for TB history, Opportunistic infection history and, finally, the variable relating to therapy was entered into the models one by one. AZT Table 3.11: Adjusted odds ratios for the retained explanatory variables for CD4 (n = 151) CD4 response at 1 year sex n (explanation) Description Odds Ratio Standard Error Z Score Probability 95% CI (males=41) 0.36 0.14 -2.63 0.009 oihistory (present=65) 1.72 0.61 1.53 0.125 0.17 – 0.77 0.86 3.45 tbhistory (present = 37) Participants’ gender History of opportunistic infections History of TB 0.82 0.33 -0.49 0.627 0.37– 1.81 artreg Groups included in final analysis Regimen 4 0.75 0.27 -0.80 0.424 0.371.51 ART regimen AZT+3TC+EFV Post-regression analysis demonstrated an area under the ROC curve of 0.66 (Figure 3.1) and the Pearson’s Goodness of fit test was statistically nonsignificant (P = 0.51) indicating satisfactory goodness of fit. 39 0.50 0.25 0.00 Sensitivity 0.75 1.00 A.B. ADEBANJO 2010 0.00 0.25 0.50 1 - Specificity 0.75 1.00 Area under ROC curve = 0.6597 Figure 3.1: ROC curve for CD4 response Table 3.12: Adjusted odds ratios for the retained explanatory variables for Haemoglobin (n = 151) Haemoglobi n response at 1 year sex oihistory n (explanation ) (males=41) Description (present=65) History of opportunistic infections Age of participants History of TB age tbhistory (present=37) Participants’ gender Odds Rati o 6.25 Standar d Error Probabilit y 95% CI 2.86 Z Scor e 4.00 0.000 0.60 0.25 -1.23 0.220 0.97 0.02 -1.57 0.117 2.20 1.04 1.66 0.096 2.54 – 15.3 3 0.26 1.36 0.941.01 0.87– 5.56 40 A.B. ADEBANJO 2010 artreg Groups included in final analysis Regimen 4 ART regimen AZT+3TC+EF V 0.25 0.11 -3.07 0.002 0.100.60 Post-regression analysis demonstrated an area under the ROC curve of 0.77 (Figure 3.2) and the Pearson’s Goodness of fit test was statistically non- 0.50 0.25 0.00 Sensitivity 0.75 1.00 significant (P = 0.24) indicating satisfactory goodness of fit. 0.00 0.25 0.50 1 - Specificity 0.75 1.00 Area under ROC curve = 0.7703 Figure 3.2: ROC curve for Haemoglobin response. Table 3.13: Adjusted odds ratios for the retained explanatory variables for Weight (n = 151) Weight n Description Odds Standard Z Probability 95% 41 A.B. ADEBANJO 2010 response at 1 year sex (explanation) (males=41) Participants’ gender History of TB tbhistory artreg Ratio Groups included in final analysis Regimen 4 Error Score CI 0.45 0.17 -2.19 0.029 2.14 0.87 1.87 0.062 0.77 0.27 -0.75 0.451 0.20 – 0.91 0.96– 4.74 ART regimen AZT+3TC+EFV 0.391.52 Post-regression analysis demonstrated an area under the ROC curve of 0.66 (Figure 3.3) and the Pearson’s Goodness of fit test was statistically non- 0.50 0.25 0.00 Sensitivity 0.75 1.00 significant (P = 0.83) indicating satisfactory goodness of fit. 0.00 0.25 0.50 1 - Specificity 0.75 1.00 Area under ROC curve = 0.6390 Figure 3.3: ROC curve for Weight response. 42 A.B. ADEBANJO 2010 TDF Table 3.14: Adjusted odds ratios for the retained explanatory variables for CD4 (n = 151) CD4 response at 1 year sex n (explanation) Description Odds Ratio Standard Error Z Score Probability (males=57) Participants’ gender History of TB 0.98 0.13 -1.25 0.211 2.14 0.87 1.87 0.062 0.77 0.27 -0.75 0.451 tbhistory artreg Groups included in final analysis Regimen 2 95% CI 0.96 – 1.01 0.96– 4.74 ART regimen TDF+3TC+EFV 0.391.52 Post-regression analysis demonstrated an area under the ROC curve of 0.63 (Figure 3.4) and the Pearson’s Goodness of fit test was statistically nonsignificant (P = 0.61) indicating satisfactory goodness of fit. 43 0.50 0.25 0.00 Sensitivity 0.75 1.00 A.B. ADEBANJO 2010 0.00 0.25 0.50 1 - Specificity 0.75 1.00 Area under ROC curve = 0.6284 Figure 3.4: ROC curve for TDF CD4 response Table 3.15: Adjusted odds ratios for the retained explanatory variables for TDF Weight response (n = 151) Weight response at 1 year sex n (explanation) Description Odds Ratio Standard Error Z Score Probability (males=57) 0.27 0.12 -3.02 0.003 tbhistory (present = 62) Participants’ gender History of TB 2.15 0.84 1.96 0.050 oihistory (present=60) History of opportunistic infections ART regimen 1.84 0.66 1.67 0.095 0.90 3.78 TDF+3TC+EFV 0.87 0.41 -0.30 0.767 0.34- artreg Groups included in final analysis Regimen 2 95% CI 0.12 – 0.63 1.00– 4.61 44 A.B. ADEBANJO 2010 2.20 Post-regression analysis demonstrated an area under the ROC curve of 0.70 (Figure 3.5) and the Pearson’s Goodness of fit test was statistically non- 0.50 0.25 0.00 Sensitivity 0.75 1.00 significant (P = 0.25) indicating satisfactory goodness of fit. 0.00 0.25 0.50 1 - Specificity 0.75 1.00 Area under ROC curve = 0.7041 Figure 3.5: ROC curve for TDF Weight response Table 3.16: Adjusted odds ratios for the retained explanatory variables for TDF HB response (n = 151) HB response at 1 year sex n (explanation) Description Odds Ratio Standard Error Z Score Probability (males=57) 2.08 0.80 1.91 0.056 oihistory (present=60) 1.20 0.47 0.47 0.642 artreg Groups included in Participants’ gender History of opportunistic infections ART regimen 95% CI 0.98 – 4.43 0.60 2.57 45 A.B. ADEBANJO 2010 final analysis Regimen 2 TDF+3TC+EFV 4.87 3.73 2.07 0.039 1.0921.87 Post-regression analysis demonstrated an area under the ROC curve of 0.65 (Figure 3.6) and the Pearson’s Goodness of fit test was statistically non- 0.50 0.25 0.00 Sensitivity 0.75 1.00 significant (P = 0.67) indicating satisfactory goodness of fit. 0.00 0.25 0.50 1 - Specificity 0.75 1.00 Area under ROC curve = 0.6551 Figure 3.6: ROC curve for TDF haemoglobin response 46 A.B. ADEBANJO 2010 CHAPTER 4 Discussion This Study This study was carried out to compare clinical and immunological response patterns in patients taking AZT and TDF-containing ART regimens and to possibly predict which of the regimen would be better and within which population. Despite the perceived mismatch between two NRTIs it can be concluded from the results of this study that, overall, the inclusion of AZT in treatment regimen showed a modest protective effect over the TDF counterpart as measured by the endpoints of the discriminative powers of the Receiver Operating Curves of the explanatory variables being 66% 77% and 66% for CD4, Haemoglobin and Weight respectively, and 63% 70% and 65% for the same variables in the AZT and TDF arms of the study respectively. After each of the a priori chosen variables, namely age and gender were tested for effect modification; TB history in patients was identified in this study as a potential effect modifier during statistical analysis. For this reason the analysis was stratified and estimates of effectiveness were determined separately for patients identified to be with or without TB during the course of the study only. Reference must quickly be made to the fact the history of affectation with TB was assessed at baseline only. In the population of patients with neo tuberculosis infection during the course of this study, therapy with HAART showed a protective effect against TB. There were 5 cases reported during this period, 2 and 3 for the AZT and TDF arms respectively representing a mere 1.7% of the entire study population and were subsequently dropped from the study population. The reported cases were perceived to have occurred as part 47 A.B. ADEBANJO 2010 of unmasking of latent TB infections and more remotely, the immune reconstitution inflammatory syndrome. From this study it seems that the role of age is vital if the expected response to treatment is to be achieved. Patients in the age range 35 - 44 had the least response to CD4 in the AZT arm of the study. Odds ratio 1.72 [95% CI 0.79 3.74], and this is found to be the same pattern in the TDF arm as well with odds ratio 1.50 [95% CI 0.64 - 3.51] Response to treatment across the study followed the expected pattern. The aim of therapy is to achieve optimal response and the study showed this to great deals with respect to outcomes of interest. However in the TDF arm of the study haemoglobin response failed to show concordance with respect to therapy. Odds ratio 5.52 [95% CI 1.24 - 24.5]. Judging by the wide Confidence Interval the reason might be because of a low number of patients in that category who satisfied the concept of response as defined in the study. Possible limitations of the study The study was done in a population of Basothos who are natives of the Mountain Kingdom of Lesotho, a country completely embedded within South Africa and with a relatively constant GDP and no form of economic growth over the last 4 years. A GDP of USD1500 effectively places the country among the poorest nations in the world. This population differ substantially from the average South African population with respect to education level, economic status and other socio-economic factors. It is an established fact that the percentage of people with health insurance in the country is negligible making holistic and comprehensive HIV care almost a non-existent feature. In addition to this the unique terrain of the country makes it extremely difficult to achieve good coverage with respect to HIV care. This makes facilities providing care resource poor. The singular gold standard monitoring tool for patients on 48 A.B. ADEBANJO 2010 HAART is the viral load. However CD4 count may be used to monitor response to therapy and alongside proper monitoring of some clinical parameters, an effective monitoring of patients can be achieved particularly in resource-poor settings. In ideal settings, with regards to the study design a prospective randomised controlled trial with possibly more patients in each arm and viral load assay would have been better; although the cost and manpower would have been difficult to reach with the resources that were available for this study. 49 A.B. ADEBANJO 2010 Bias and Confounding An attempt to reduce bias as made throughout this study. Firstly the selection of patient files into both arms of the study was by random selection via computer-generated number thereby preventing the selection of patients with poor care to be compared to patients with better care into the study (Selection bias). This is evident in the absence of significant difference between the baseline parameters. Secondly for the AZT arm of the study, the same person audited the patient records and entered data into the collection sheets at 12 months. The person performing the recording for the TDF arm of the study was the same throughout the study. Observer bias was therefore limited. All doctors attending to patients in the clinic were blinded to which patients were selected for the study. Confounding by the Hawthorne effect (The non-specific beneficial effect of taking part in research) was impossible owing to the study design. Study results in relation to other studies Process measures Data from the baseline figures of this study compare well to those of studies elsewhere in the world[55]. What is clearly different in these other studies is that dual HIV therapy was used in some and a combination of three NRTIs was used in some others to provide triple therapy with regards to the AZT arm. With respect to the TDF arm, there is paucity of information regarding therapy with NNRTIs. A study done in the USA compared responses between AZT 3TC 50 A.B. ADEBANJO 2010 and EFV with TDF FTC (Emtricitabine) and EFV. Two things readily come to mind from these studies. No therapy with NVP and viral load assay was an integral aspect of monitoring and final evaluation in the study. Furthermore a CD4 cut off was never established at entry into the study by participants as any CD4 level was acceptable at baseline. Viral load of greater than 10000 copies per ml of blood was the acceptable viral load level for entry.[56,57,58] With respect to this study, there is evidence that the adoption of two NRTIs and one NNRTI achieved similar response even in the event of severely compromised immune function. Outcome measures Largely speaking the results of the outcomes of this study compared very favorably with their American counterparts where resources abound and even though the time frame for preliminary assessments differ, the end results were quite similar. [58] Questions arising from this study for further study. The first question arising is: How best should the database be managed in order to be able to generalize this study. Secondly, with the perennial problems associated with bone marrow toxicity leading to poor adherence to AZT-containing treatments, has this study been able to show that the incidence is quite neglible since none of the participants in this study developed such an event? It may be argued that this group of patients may have been excluded owing to sampling but haemoglobin levels or anaemia were not criteria to include or exclude patients in the study. On the 51 A.B. ADEBANJO 2010 other hand, how possible is it to determine patients that may go on to develop anaemia secondary to AZT administration. Thirdly, what will happen to the patients that can't even afford a hospital visit more than once or twice in a year owing to transportation difficulties? Can this study be employed in their care? 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