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SCREENING FOR DISEASES Dr.MUSTAQUE AHMED MBBS,MD(COMMUNITY MEDICINE), FELLOWSHIP IN HIV/AIDS OBJECTIVE OF THE CLASS TO UNDERSTAND THE DEFINATION OF SCREENING AND LEAD TIME. TO KNOW OBJECTIVES OF SCREENING AND TYPES OF SCREENING. 2 SCREENING DEFINATION: The search for unrecognized disease or defect by means of rapidly applied tests, examinations or other procedures in apparently healthy individuals 3 “LEAD TIME” The advantage gained by screening First possible time of diagnosis Usual time of diagnosis Outcome A-usual outcome B- better outcome “LEAD TIME” 4 CONCEPT OF LEAD TIME •Lead time is the period between diagnosis by early detection and diagnosis by other means. •This period , determine both the severity of the disease and the success of any treatment in reversing the disease process. •Hence, screening programmes should therefore concentrate on those DISEASE where the LEAD TIME IS LONG. 5 AIMS AND OBJECTIVES: Early detection and lifestyle changes. Early intervention and management. To reduce the risk of disease . To decrease mortality and suffering. 6 Which diseases to be screened? 1. 2. 3. 4. 5. 6. Important public health problem Recognizable early asymptomatic case Test to detect disease prior to onset of signs and symptoms Facilities available for confirmation of diagnosis Effective treatment available Early detection reduces morbidity and mortality 7 TARGET GROUPS: Persons with a family history of a disease. Persons with occupational exposure to disease causing substance. Pregnant women. Workers responsible for the lives of others i.e., pilots, bus drivers. 8 SCREENING AND DIAGNOSTIC TEST: A screening test is not intended to be a diagnostic test. It is only an initial examination. Screening and diagnostic test my be contrasted as:- Screening test Diagnostic test • Done on apparently healthy. • Done on those with indications of sick. • Applied to groups. • Applied to single patients. • Less accurate. • More accurate 9 • Based on one criterion. • Based on evaluation of a number of symptoms and lab findings. •Less expensive. • More expensive. •Not a basis for treatment. •Used as a basis for treatment. •The initiative comes from the investigator or agency providing care. •The initiative comes from a patient with a complaint. 10 USES OF SCREENING: Case detection. Control of disease. Research purposes. Educational opportunities. 11 CASE DETECTION: •Also known as ‘ prescriptive screening’. •Here the people are screened primarily for their own benefit. •Specific diseases sought by this method arebreast cancer cervical cancer diabetes mellitus iron deficiency 12 CONTROL OF DISEASE: •Also known as ‘ prospective screening’. •People are examined for the benefit of others. eg,1) screening of immigrants from infectious diseases like T.B and syphilis to protect the home population. 2) screening for streptococcal infection to prevent rheumatic fever. 13 RESEARCH PURPOSES: •Screening may sometimes be performed for research purposes. eg, to know the history of many chronic diseases like cancer, HTN etc. EDUCATIONAL OPPORTUNITIES: •Screening programmes help in - providing opportunities for creating public awareness. - for educating health professionals. 14 TYPES OF SCREENING: 3 TYPES Mass screening. High risk / selective screening. Multiphasic screening. 15 MASS SCREENING Def- Organized periodic procedures performed on large Groups of people for the purpose of detecting disease. Eg.TB It is offered to all irrespective of the particular risk individuals. •This procedure received support in the past, but it was subjected to critical review. •Indiscriminate mass screening, therefore is not a useful preventive measure unless backed up by suitable treatment that will reduce the duration of illness. 16 HIGH RISK / SELECTIVE SCREENING: •Screening will be most productive if applied selectively to high risk groups, the groups defined on the basis of epidemiological research. eg, 1) cancer cervix tends to occur relatively less often in the upper social groups, screening for cancer cervix in the lower social groups could increase the yield of new cases. 2) increase serum cholesterol level in individual---for CHD 17 MULTIPHASIC SCREENING: Def- simultaneous examination of a population for several different diseases by using 2 or more screening test. e.g., chemical and haematological tests on blood and urine specimens) Randomized controlled studies in U.K and USA suggested that multiphasic screening has not shown any benefit accruing to the population in terms of mortality and • morbidity reaction. It has also increased the cost of health services without any observable benefits. 18 19