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ISSN 0017-8748
doi: 10.1111/j.1526-4610.2011.01866.x
Published by Wiley Periodicals, Inc.
Headache
© 2011 American Headache Society
Research Submission
Preventive Medication Adherence in African American and
Caucasian Headache Patients
head_1866
520..532
Bernadette D. Heckman, PhD; Gary Ellis, MS
Study Objectives.—To examine race-related differences in adherence to preventive medication agents in headache patients
and identify factors predictive of medication adherence in Caucasian and African American headache patients.
Methods.—Using a longitudinal naturalistic study design, data from 77 Caucasian and 32 African American headache
patients were collected through (1) 30-day daily diaries that assessed medication adherence, headache frequency, and headache
episode severity; (2) self-administered surveys that assessed headache management self-efficacy; and (3) telephoneadministered psychiatric interviews that yielded psychiatric diagnoses. Using daily diary adherence data, patients’ adherence to
preventive agents was dichotomized as “Inconsistent” (ie, adhered fewer than 80% of days) or “Consistent” (ie, adhered ⱖ80%
of days during the past month).
Results.—The proportion of adherent African American patients (69%) did not differ significantly from the proportion of
adherent Caucasian patients (82%). Exploratory univariate logistic regression analyses found that preventive medication
adherence levels of 80% or less were associated with being diagnosed with major depressive disorder and lower levels of
headache management self-efficacy.
Conclusions.—Future research should test if interventions that reduce depressive symptoms and increase patients’ levels
of headache management self-efficacy can produce concomitant increases in adherence to preventive headache agents.
Key words: headache, medication adherence, race-related health disparities
Abbreviations: AIDS acquired immune deficiency syndrome, ANOVA analysis of variance, HIV human immunodeficiency
virus, HMSE headache management self-efficacy, ICHD-II International Classification of Headache Disorders,
2nd Edition, MEMS medication event monitoring system, PRIME-MD Primary Care Evaluation of Mental
Disorders
(Headache 2011;51:520-532)
schedules is associated with greater mortality, more
rapid disease progression, more frequent hospitalizations, and poorer clinical health outcomes in patients
with a variety of chronic health conditions.4-7 Moreover, in the USA alone, the economic impact of
appointment and medication nonadherence exceeds
$100 billion dollars annually.8 While medication
adherence has been studied extensively across a
variety of health conditions, such as human
immunodeficiency virus/acquired immune deficiency
Approximately 30% to 60% of patients living
with chronic health conditions report inconsistent
adherence to medication regimens (ie, typically
ⱕ80%).1-3 Inconsistent adherence to medication
From the Department of Psychology, Ohio University, Athens,
OH, USA.
Address all correspondence to B.D. Heckman, Department of
Psychology, Ohio University, Athens, OH 45701, USA.
To download a podcast featuring further discussion of this
article, please visit www.headachejournal.org
Conflict of Interest: There are no conflicts of interests associated with this study.
Accepted for publication January 23, 2011.
520
Headache
syndrome (HIV/AIDS),9,10 cardiovascular disease,11
and asthma,12 far less research has examined medication adherence in patients with headache disorders.
Pharmacological treatments for headache episodes include abortive agents, such as triptans, oral
nonsteroidal anti-inflammatory drugs, or combination
analgesics taken during the course of the headache
attack to stop or limit headache symptoms.13
However, the overutilization of abortive headache
medications can lead to medication overuse headaches, also known as “rebound headaches.”13 For
individuals who experience frequent headaches,
preventive (ie, prophylactic) pharmacotherapies,
such as b-blockers, anticonvulsants, and tricyclic
antidepressants/selective serotonin reuptake inhibitors (SSRIs), are indicated treatments and significantly reduce the number of headache attack days,
improve daily physical functioning, and enhance
headache patients’ overall quality of life.14-18
The benefits of preventive headache agents,
however, are largely dependent upon consistent
adherence (although minimum levels of adherence
that must be achieved to obtain clinical benefits in
this population are unknown). Packard et al19 found
a low level of adherence (52%) to acute and preventive headache agents in patients with headache disorders, suggesting that patients found it difficult to
adhere consistently to headache medications or
that adherence-related benefits did not outweigh
adherence-related challenges in many patients (eg,
economic costs, negative side effects, and perceived
inefficacy of treatments). An additional explanation
for low rates of medication adherence in headache
patients is that, compared with many other chronic
illnesses, such as diabetes, osteoarthritis, and HIV/
AIDS, headaches can be relatively intermittent in
nature (eg, some patients experience only a few headaches per month), which may predispose some headache patients to poorer adherence.
Only 2 studies have specifically examined adherence to preventive agents in headache patients.
Steiner et al20 investigated adherence to pizotifen in
migraine patients in a headache specialty clinic.
Patients took the correct number of pills on 58% of
days over an 8-week period; however, only 32% of
doses were taken on schedule during this period.
521
Mullerners et al21 examined adherence to preventive
medications in migraine patients in a London headache specialty clinic. When assessed via self-report
pill-count, the average 2-month adherence rate was
91%. However, during the same time period, medication event monitoring systems (MEMS) recorded a
mean adherence rate of only 66% (suggesting that
self-report may inflate adherence rates in headache
patients). When regimen complexity was considered,
patients taking only 1 medication dosage per day selfreported an adherence rate of 79%, patients prescribed twice-daily preventive medications reported a
60% adherence rate, and patients prescribed a 3-time
daily preventive medication reported an adherence
rate of 54%. It is important to note, however, that
these studies were based on small samples (eg, n = 4
and n = 29, respectively). The low rates of adherence
reported in these studies underscore the need to
better understand, and potentially intervene upon,
medication adherence in headache patients.
No research has examined if race-related differences in medication adherence observed in persons
with other chronic health conditions (eg, AIDS,
diabetes)22-25 generalize to individuals with headache
disorders or if predictors of medication adherence
differ by race. Racial differences in adherence to
headache medications have not been studied even
though: (1) 3.3% of African Americans in the USA
are diagnosed with a headache disorder;26 (2) African
Americans living with a variety of chronic health
conditions (eg, HIV/AIDS, hypertension, diabetes)
often report poorer adherence to medication regimens than Caucasians;27-30 and (3) African American
and Caucasian headache patients respond equally
well to contemporary preventive pharmacotherapies,
highlighting the importance of maximizing medication adherence in both racial groups.31
This exploratory study examined rates and predictors of adherence to preventive medication agents
in patients in headache subspecialty treatment clinics
and if predictors of adherence differed by race. The
study tested the following 5 hypotheses (the rationale
for each is described in detail below): (1) African
Americans would report lower rates of medication
adherence than Caucasians; (2) patients diagnosed
with major depressive disorder (MDD) would report
522
poorer medication adherence than patients with no
diagnosis of MDD; (3) patients with greater headache
management self-efficacy (HMSE) would report
more consistent medication adherence; (4) headache
frequency would predict medication adherence more
strongly in African Americans than in Caucasians;
and (5) headache episode severity would predict
medication adherence more strongly in African
Americans than Caucasians.
African Americans report poorer adherence to
medication regimens than Caucasians across a
number of chronic health conditions, including HIV/
AIDS, hypertension, and diabetes.25-28 Poorer rates of
medication adherence in African Americans compared with Caucasians have been observed across
different adherence assessment methodologies,
including self-report,32 pharmacy refills,33 and
MEMS.34 Reasons for poorer medication adherence
in African Americans in the USA include cost concerns,35 beliefs that medications are symbols of
mental illness,36 fear of becoming addicted to medications,36 and conspiracy beliefs regarding the healthcare system and the use of pharmacotherapies with
African Americans in the USA.37
The hypothesis that being diagnosed with MDD
would lead to poorer medication adherence in headache patients is based on several studies linking
depression with poor adherence in other illnesses.22-24
Patients with MDD may experience cognitive symptoms of depression that result in one forgetting to
take medications and/or confusion about one’s
medication regimen. Moreover, depressed headache
patients may experience increased apathy, low selfesteem, and overly pessimistic and irrational thoughts
about medication efficacy, resulting in poorer medication adherence.
The hypothesis that greater HMSE would
promote greater medication adherence is based
on numerous studies demonstrating a positive
relationship between self-efficacy and medication
adherence.38-46 Self-efficacy is a person’s beliefs about
his/her abilities to influence events and behaviors that
affect one’s life.47 Headache patients who are confident that they can effectively prevent and manage
their headaches are likely to adhere more consistently to headache medication regimens. Conversely,
April 2011
headache patients who lack a sense of mastery or who
have difficulty managing their headaches (based
either on current headache activity or past headache
management failures) may question their headache
management skills and experience greater difficulty
adhering to medication regimens.
Finally, this study tested the hypothesis that
patients who reported more severe and frequent headaches at treatment initiation would report greater
headache medication adherence at 6-month follow-up
but that these relationships would be stronger in
African Americans than in Caucasians. These predictions are based on clinical and experimental research
showing that African Americans report less pain tolerance and greater pain unpleasantness than their
Caucasian counterparts.48,49 Because of their heightened sensitivity to pain,African Americans with more
severe and frequent headaches at treatment initiation
are expected to perceive a greater need to adhere
more consistently to preventive headache agents to
better manage their headache disorders. Findings
from the current study can identify individuals at
elevated risk for poor adherence to preventive headache agents and inform the development of culturally
contextualized interventions to increase preventive
medication adherence in headache patients.
METHODS
Participants and Inclusion Criteria.—This study
was a secondary analysis of a larger dataset of 311
patients in a longitudinal study that examined racerelated differences in headache treatment outcomes.
Of the 311 patients enrolled in the original study, 109
(77 Caucasian and 32 African American headache
patients) provided adherence data through 30-day
daily diaries. Between July 2004 and June 2008, all
patients were recruited into the study through 4 outpatient headache specialty treatment clinics located
in Cincinnati, Cleveland, Columbus, and Toledo,
Ohio. Study inclusion criteria were: (1) 18 years of age
or older; (2) self-identifying as African American or
Caucasian; (3) meeting International Classification of
Headache Disorders, 2nd Edition (ICHD-II) criteria50 for episodic migraine, chronic migraine, episodic
tension-type headache, or chronic tension-type headache; (4) the physician believed that the patient
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523
Pre treatment
Visit
Patient enters
treatment
0
1-Mo FU Visit
Patient begins
new preventive
therapy
1
2-Mo FU Visit
2
Patients
complete
the first 30-day
daily diary
6-Mo FU Visit
3
Months
4
5
6
Patients
complete
the second 30-day
daily diary
Figure.—Study design. FU = follow-up; Mo = month.
would benefit from a new preventive headache agent;
and (5) the patient was willing to delay the initiation
of new preventive treatment for 1 month (so that
pretreatment headache activity could be recorded).
The project’s protocol was approved by the university’s institutional review board and no adverse events
were reported during the study. Previous publications
from this dataset have examined how treatment
appointment attendance51 and treatment outcomes
differ by patient race,31 how treatment outcomes
relate to the presence of a psychiatric condition,52 and
the extent to which commonly used psychosocial
headache measures are appropriate for use with Caucasian and African American headache patients.53
Procedure.—Recruitment brochures that described the study were distributed to potential
patients in reception areas and waiting rooms of participating clinics as they awaited treatment. Because
patients of color were relatively underrepresented in
all 4 treatment centers, all racial minority patients who
presented for treatment were approached for study
enrollment. The larger pool of Caucasian patients
enabled the project to use a recruitment strategy in
which only every fifth Caucasian patient was
approached for study enrollment. Eligible patients
who decided to enroll into the study provided written
informed consent in the treatment clinic.
As shown in the Figure, the study used a prospective, longitudinal design and assessed patients at pre-
treatment and 1-, 2-, and 6-month follow-up. These
follow-up time periods were used because they represented patients’ typically scheduled visits to participating clinics. Acute therapies were either initiated or
adjusted by study physicians at the patients’ pretreatment visit. Patients were reevaluated during the
second visit that occurred 1 month after the pretreatment visit. During this visit, study physicians assessed
the need for preventive medication(s) using the
30-day headache diary completed by the patient.
Patients determined to be in need of preventive a
gents were prescribed medications as clinically indicated. Patients were then scheduled to participate in
2- and 6-month follow-up visits. The study’s experimental design and procedures are described in
greater detail elsewhere.31
Assessment Methodologies.—Headache Diagnosis.—During the initial patient–physician interaction, the physician diagnosed the patient’s current
headache disorder(s) using ICHD-II.50 The physician
also documented the patient’s past and current pharmacological headache treatments.
Psychiatric Diagnosis.—Psychiatric disorders
were diagnosed using the Primary Care Evaluation of
Mental Disorders (PRIME-MD).54 The PRIME-MD
was administered by trained research staff during a
telephone interview conducted within 2 days after the
pretreatment visit. The PRIME-MD yields a subset of
diagnoses included in the Diagnostic and Statistical
524
Manual of Mental Disorders, including mood and
anxiety disorders, alcohol and substance abuse/
dependence disorders, eating disorders, and
somatoform disorders. In this study, the PRIME-MD
was used to identify patients with MDD (0 = no,
1 = yes).
30-Day Daily Headache Diary.—At the conclusion of the pretreatment visit, each patient received a
self-administered, paper-and-pencil daily diary to
record the frequency and severity of headaches experienced during the assigned 30-day period. The first
30-day period was the interval between the patient’s
initial assessment and his or her second visit (when
new preventive therapy was prescribed). This headache diary was also completed during the 30 days that
followed the patient’s 6-month follow-up visit. Headache frequency was operationally defined as the
number of days over the 30-day period during which
patients experienced a “mild” “moderate,” or
“severe” headache.” Headache episode severity was
assessed for each headache using a 4-point scale
(1 = “No pain,” 2 = “Mild,” 3 = “Moderate,” or
4 = “Severe”). On days that patients did not experience a headache, a value of “1” was recorded. On days
that patients did experience a headache, the severity
of the headache episode was rated using response
options “2” through “4.” Mean headache episode
severity was calculated by summing headache severity ratings and dividing this sum by the number of
headaches the patient experienced over the 30-day
reporting period.
Preventive Medication Adherence.—Adherence
to preventive medication was assessed only in the
30-day headache diary that followed the 6-month
follow-up visit. Based on patients’ daily diary
responses, adherence to preventive medication agents
was dichotomized as 0 = “Inconsistent” (ie, adhered
to medication regimens on fewer than 80% of days)
or 1 = “Consistent” (ie, adhered to medication regimens on 80% of more days during the past month).
Eighty percent adherence to medication regimens
is a common operational definition of adequate
medication adherence across a number of health
conditions.1-3
Headache Management Self-Efficacy Scale.—The
25-item HMSE scale55 assessed patients’ confidence
April 2011
that they could prevent and manage headaches.
Respondents rated the extent to which they agreed
with each item using a 7-point scale (1 = “Strongly
disagree” to 7 = “Strongly agree”). The HMSE evidenced good internal consistency in the current study
(a = 0.90).
Demographic Characteristics.—Patients provided
data on their age, gender, socioeconomic status,
health insurance status (health maintenance organization, preferred provider organization, private,
social security disability insurance), and selfselected the racial category with which they most
identified.
Data Analytic Procedures.—Data screening analyses evaluated the distributions of study variables (eg,
skew, kurtosis) and identified potential univariate and
bivariate outliers. Differences between Caucasians
and African Americans at treatment initiation were
examined using analysis of variance (ANOVA) and
chi-square. Chi-square analyses tested if race was
associated with type of acute or preventive medication agents prescribed to patients. Several exploratory univariate logistic regression analyses sought to
identify individual predictors of the dichotomized
medication adherence measure (0 = “Inconsistent,”
1 = “Consistent”). Specifically, separate regression
analyses examined if medication adherence was
related to patients’ race, age, education, gender, being
diagnosed with MDD (yes/no), headache frequency
at pretreatment, headache episode severity at
pretreatment, and HMSE at pretreatment. Three
exploratory interaction terms (ie, “Race ¥ MDD
Status,” “Race ¥ Headache Frequency,” and “Race ¥
Headache Severity”) were also examined in separate
univariate logistic regression analyses to determine if
these interactions predicted medication adherence.
The regression analyses were exploratory in that they
did not test a formal theoretical model that might
explain preventive medication adherence in headache patients. Instead, these regression analyses
tested if individual variables (or 2-way interactions
involving race) predicted adherence. All data analyses were conducted using spss Version 18 (PASW
Statistics). All inferential statistical analyses that
tested a priori study hypotheses used a ⱕ 0.05,
2-tailed.
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525
RESULTS
Demographics and Headache Diagnoses.—As
shown in Table 1, the average patient was female
(89%), 36.6 years of age (SD = 10.4, Min = 18,
Max = 66), had completed 13.9 years of education,
and reported an annual income of less than $60,000
(87%). Ninety-nine percent of patients had some
form of health insurance. Seventy percent of patients
received a headache diagnosis of migraine and 54%
received a diagnosis of tension-type headache at their
initial visit. Patients experienced 1 or more headaches
on 17.2 days during the past month (Min = 1,
Max = 30, SD = 7.7). Thirty-one percent of all patients
were diagnosed with MDD.
Table 1 shows the demographic characteristics of
the 173 Caucasian and 111 African American patients
who completed pretreatment assessments and the 79
Caucasian and 32 African American patients who
completed 6-month follow-up assessments (although
2 of the 79 Caucasians who completed 6-month
follow-up assessments did not provide adherence
data). Chi-square tests of association and 1-way
ANOVA characterized associations among race,
demographic variables, headache diagnoses, and
headache characteristics at pretreatment and
6-month follow-up. Table 1 shows that, at pretreatment, African American patients were older, slightly
more likely to be female, reported fewer years of
education, were more likely to be diagnosed with
MDD, reported more headache days per month,
reported more severe headache episodes, and were
less likely to be diagnosed with migraine as their
primary headache disorder compared with Caucasians (all Ps < .05). Table 1 also shows that among the
79 Caucasians and 32 African Americans who completed 6-month follow-up assessment instruments,
African Americans were more likely to be female and
report annual incomes below $60,000 (P < .05).
Table 2 shows that, at the end of the 6-month
follow-up period, preventive agents prescribed frequently to Caucasian patients included anticonvulsants (33.1%), antidepressants (31%), and “other”
preventive therapies (eg, low-dose aspirin, nonsteroidal anti-inflammatories; 33.1%). Triptans or
Table 1.—Sociodemographic Characteristics and Headache Diagnoses of Caucasian and African American Patients
Characteristic
Age (years)
Years of education
Income below $60,000
Being female
ⱖ80% medication adherence
Diagnosed with major
depressive disorder
Headache days/month
Headache episode severity
Diagnosed with migraine
(episodic or chronic, with
or without aura)
Diagnosed with TTH
(episodic or chronic)
6-month
Pretreatment
Overall
follow-up
Pretreatment
sample
pretreatment
sample
sample
African
c2 or t
sample
Caucasians
Americans pretreatment Caucasians
sample†
(n = 284)
(n = 79)
(n = 173)
(n = 112)
6-month
follow-up
sample
African
Americans
(n = 32)
c2 or t
6-month
follow-up
sample‡
36.6 ⫾ 10.4
13.9 ⫾ 2.2
88.8%
87.8%
n/a
30.5%
35.6 ⫾ 10.2
14.3 ⫾ 2.1
88.7%
85.2%
n/a
24.1%
38.4 ⫾ 10.5
13.5 ⫾ 2.3
88.8%
92.1%
n/a
40.4%
2.2**
2.7***
0.1
2.8*
n/a
8.3***
36.5 ⫾ 10.5 40.8 ⫾ 11.2
14.4 ⫾ 2.1 13.7 ⫾ 2.1
81.3%
100%
84.4%
100%
82%
69%
24.7%
34.4%
1.7
2.8
6.7**
5.4**
1.6
1.1
17.2 ⫾ 7.7
2.64 ⫾ 0.3
69.6%
16.6 ⫾ 7.9
2.61 ⫾ 0.3
76.0%
18.2 ⫾ 7.3
2.70 ⫾ 0.4
59.8%
2.1**
2.2**
8.4***
11.9 ⫾ 7.6
2.54 ⫾ 0.3
–
14.3 ⫾ 7.7
2.51 ⫾ 0.3
–
1.5
0.4
–
53.7%
57.3%
48.2%
–
–
*P < .10; **P < .05; ***P < .01.
†Caucasians and African Americans compared at baseline.
‡Caucasians and African Americans compared at 6-month follow-up.
TTH = tension-type headache.
2.3
–
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April 2011
Table 2.—Preventive and Acute Medications Prescribed to Patients by Race
Caucasians (%)
Treatment
Preventive medication
Antidepressant
Anticonvulsant
b-blocker
Calcium blocker
Other (NSAS, low-dose aspirin, Botox)
Acute medication
Simple and compound analgesic
Compound analgesics with codeine/barbiturate
Triptans or ergotamine
Adjunctive treatments (antiemetics, etc)
African Americans (%)
1-month
follow-up
6-month
follow-up
1-month
follow-up
6-month
follow-up
19.9
27.5
9.4
2.3
12.9
31.0
33.1
11.3
2.8
33.1
27.3
24.5
10.9
4.5
6.4
42.1
30.7
13.6
5.7
26.1
25.1
2.3
41.5
25.7
28.9
2.8
42.3
26.1
23.6
2.7
32.7
25.5
25.0
1.1
35.2
25.0
No between-group or within-group pairwise comparisons were significant at P < .05.
ergotamines were the most widely prescribed acute
medications for Caucasians (42.3%). Among African
American patients, the most widely prescribed
preventive therapies were antidepressants (42.1%),
anticonvulsants (30.7%), and “other” preventive
therapies (26.1%). The most common acute medications prescribed to African Americans were triptans
or ergotamines (35.2%). The large proportion of
African American patients prescribed antidepressants is noteworthy given that African Americans
(40.4%) were significantly more likely than Caucasians (24.1%) to be diagnosed with MDD. No significant race differences were found in preventive or
acute medication prescription practices (all Ps > .10).
Adherence
Data Collection by Race.—
Significantly fewer African Americans (28.1%;
32/114) provided adherence data compared with
Caucasians (44.5%; 77/173) via 30-day daily diaries
completed after the 6-month follow-up, c2(1) = 7.9,
P < .005. To examine whether patients who provided
adherence data differed from patients who did not
provide adherence data at 6-month follow-up, a series
of within-race analyses were conducted. As shown in
Table 3, within-race analyses showed that African
Americans who provided adherence data at 6-month
follow-up were comparable with African Americans
who did not provide adherence data in age, educa-
tion, annual income, being diagnosed with MDD,
headache frequency, headache severity, headache disability, headache-specific quality of life, or HMSE
assessed at pretreatment assessed at 6-month
follow-up at pretreatment (all Ps > .10). Table 3 also
shows that Caucasians who provided adherence data
at 6-month follow-up were comparable with Caucasians who did not provide adherence data at 6-month
follow-up (all Ps > .05).
Predictors of Medication Adherence.—A series of
exploratory univariate logistic regression analyses
were conducted that identified predictors of medication adherence group: 0 = “Inconsistent” (<80%),
1 = “Consistent” (ⱖ80%). Each analysis included 109
African American and Caucasian patients who provided adherence data at 6-month follow-up. Because
no demographic variable predicted adherence group,
none was employed as a covariate in the univariate
regression analyses. For regression analyses that
tested race-related interactions (ie, “Race ¥ MDD
Status,” “Race ¥ Headache Frequency,” and “Race ¥
Headache Severity”), the 2 main effects were entered
first followed by the interaction term. Rates of adherence did not vary by the 4 study sites (P > .60).
Table 4 displays the odds ratios, 95% confidence
intervals, and significance levels for each individual
predictor of adherence. A logistic regression found
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527
Table 3.—Demographic and Behavioral Differences Between Patients Who Did and Did Not Provide Adherence Data at
6-Month Follow-Up
Characteristic
Age (years)
Years of education
SES factor score
Diagnosed with MDD
Headache days/month
Headache episode severity
Headache disability inventory
Headache specific quality of life
Headache management self-efficacy
Caucasians
who provided
adherence
data (n = 77)
Caucasians
who did not
provide
adherence
data (n = 96)
37.23 ⫾ 10.5
14.4 ⫾ 2.11
.24 ⫾ .92
27.5%
16.5 ⫾ 7.6
2.57 ⫾ 0.31
1.8 ⫾ 0.52
44.8 ⫾ 13.9
93.8 ⫾ 23.9
34.1 ⫾ 9.8
14.2 ⫾ 2.1
0.1 ⫾ 0.96
32.4%
15.9 ⫾ 8.2
2.66 ⫾ 0.23
1.9 ⫾ 0.52
44.5 ⫾ 15.6
97.1 ⫾ 21.1
c2 or t
African
Americans
who provided
adherence
data (n = 32)
African
Americans
who did not
provide
adherence
data (n = 79)
c2 or t
-1.9
-0.72
-1.6
0.7
-0.40
1.5
0.83
-0.09
-0.89
40.73 ⫾ 11.4
13.7 ⫾ 2.1
-0.10 ⫾ 0.9
42.9%
18.9 ⫾ 7.3
2.63 ⫾ 0.38
2.1 ⫾ 0.5
47.9 ⫾ 16.1
93.9 ⫾ 21.1
37.3 ⫾ 9.9
13.4 ⫾ 2.4
-0.21 ⫾ 1.1
34.4%
18.9 ⫾ 7.7
2.67 ⫾ 0.26
2.0 ⫾ 0.7
48.3 ⫾ 17.7
90.5 ⫾ 23.7
-1.5
-0.49
-0.51
0.7
-0.04
0.06
-0.41
0.09
-0.65
MDD = major depressive disorder.
that the proportions of African American (69%) and
Caucasian (82%) patients who adhered consistently
to preventive medication agents during the past
month did not differ significantly, OR = 0.49, 95%
CI = 0.19, 1.26, P = .14.* Table 4 also shows that
patients who reported greater HMSE were also significantly more likely to adhere consistently to preventive headache agents, OR = 1.02, 95% CI = 1.011.05, P = .03. Finally, patients with MDD were also
less likely to adhere consistently to preventive headache agents, OR = 0.34, 95% CI = 0.13-0.87, P = .03.
None of the 2-way interactions involving Race (ie,
Race ¥ MDD Status, Race ¥ Headache Frequency, or
Race ¥ Headache Severity) predicted adherence. A
post-hoc point-biserial correlational analysis found
that HMSE and being diagnosed with MDD (the 2
strongest predictors of adherence) were significantly
and negatively correlated, r(109) = -0.29, P < .002.
*The logistic regression analysis was reconducted controlling
for patients’ age, years of education completed, gender, and
being diagnosed with MDD at pretreatment (yes/no). Similar
to the logistic regression analysis conducted without covariates,
this logistic regression analysis found that the proportion of
African American and Caucasian patients who adhered consistently to preventive medication agents during the past month
did not differ significantly, ORAdj = 0.47, 95% CI = 0.16, 1.33,
P = .15.
Specifically, headache patients diagnosed with MDD
also reported lower levels of HMSE.
DISCUSSION
This is the first exploratory study to compare
rates of adherence and identify predictors of adherence to preventive headache agents in Caucasian and
African American headache patients. Comparable
Table 4.—Predictors of Medication Adherence Group in
African American and Caucasian Headache Patients
Predictor variable
OR
95% CI
for OR
P
Age (years)
Years of education
Being female
Being African American
Headache days per month
Headache episode severity
Headache management self-efficacy
Being diagnosed with MDD
Race ¥ headache episode severity
Race ¥ headache days per month
Race ¥ major depression diagnosis
1.00
0.99
0.29
0.49
1.02
2.02
1.02
0.34
9.87
1.09
0.35
0.96-1.05
0.80-1.24
0.04-2.39
0.19-1.26
0.96-1.08
0.56-7.28
1.01-1.05
0.13-0.87
0.60-161.54
0.95-1.25
0.05-2.91
.89
.98
.25
.14
.63
.28
.03
.03
.11
.25
.36
MDD = major depressive disorder.
528
proportions of African American and Caucasian
headache patients reported consistent adherence (ⱖ
80%) to preventive headache medications in the past
month. This finding was unexpected given that
African Americans with chronic health conditions
(eg, HIV/AIDS, diabetes) often report poorer medication adherence compared with Caucasians.26,28
While both groups reported reasonably good adherence to preventive medication regimens, it is unclear
whether the ⱖ80% adherence rate recorded by both
groups (ie, 69% for African Americans and 82% for
Caucasians) are sufficient to manage patients’ headaches effectively.
The lack of race-related differences in medication
adherence in this study may be explained, at least in
part, by the differentially higher rate of treatment
dropout in African Americans compared with Caucasians. Medication adherence was assessed only at
6-month follow-up. Less than 30% of African Americans provided adherence data in the current study. It
is possible that only the most adherent African
American and Caucasian patients remained in treatment and provided adherence data at 6-month
follow-up, masking any potential race-related differences in medication adherence. Had medication
adherence been assessed earlier in the study, racerelated differences in medication adherence may
have emerged.
Headache patients diagnosed with MDD at pretreatment were less likely to adhere consistently to
headache medication regimens 6 months later.
Adherence-improvement interventions that focus on
depressed patients and that intervene simultaneously
on the patient’s adherence difficulties and depression
appear warranted. Currently, the use of antidepressant pharmacotherapies (eg, tricyclics, SSRIs) is indicated for patients who present to headache clinics
with chronic headache disorders and comorbid
depression. Cognitive-behavioral interventions56 that
eliminate maladaptive and self-defeating thoughts
and behaviors that prevent consistent adherence to
preventive headache medications may also be helpful
for depressed headache patients. In fact, cognitivebehavioral interventions have already been shown to
simultaneously reduce depressive symptoms and
improve adherence to antiretroviral therapy in
April 2011
persons living with HIV/AIDS.57 Interpersonal psychotherapy,58 which links depression to challenging
life events (eg, job loss, a bereavement, or an interpersonal dispute), should also be considered a potential
psychotherapeutic approach to alleviate headache
activity and depressive symptoms in depressed headache patients. At a minimum, all practitioners should
monitor closely rates of preventive medication adherence in their headache patients with comorbid
depressive disorders.
Headache patients who reported less HMSE at
pretreatment were also less likely to adhere consistently to preventive headache agents 6 months later.
This finding was expected given the strong relationship between self-efficacy and adherence observed
across other health disorders.38-46 This finding suggests
that headache practitioners should proactively
monitor patients’ adherence behaviors if they appear
to lack the self-confidence or skills required to adhere
consistently to preventive headache agents. Given
that headache patients who were depressed also
tended to report lower levels of HMSE, interventions
that target depressed headache patients are likely to
capture headache patients who also have low selfefficacy to adhere consistently to preventive headache agents.
Three study hypotheses were not supported in
the current study. As noted above, adherence was
unrelated to patient race. However, it is worth noting
that a greater proportion of African American
patients (40%) were diagnosed with MDD compared with Caucasians (24%). Because depression
appears to be associated with nonadherence to preventive headache agents, a disproportionately large
number of African American headache patients may
be at risk for nonadherence because of their MDD
diagnoses. Additional research is needed to examine
associations among race, MDD status, and adherence. Finally, adherence was unrelated to the “Race
by Headache Severity” and “Race by Headache Frequency” interactions. While African Americans, in
general, may have greater pain sensitivity and lower
pain thresholds,48,49 these tendencies do not appear
to result in greater rates of adherence in African
American headache patients compared with
Caucasians.
Headache
While this study identified predictors of medication adherence in headache patients, and a previous
report using this dataset identified predictors of treatment appointment nonattendance in this sample,31
predictors of the 2 health-related behaviors are likely
to differ. For example, medication adherence is likely
to be related to factors such as negative medication
side effects, medication costs, and beliefs that medications are inefficacious. Conversely, treatment appointment nonattendance may be related to factors such as
long waiting times during previous treatment
appointments, poor patient–physician relationships,
lack of transportation or child care, and severe headache activity at the time of the appointment. Future
research should continue to identify reasons for poor
medication adherence and inconsistent treatment
appointment attendance in headache patients.
The present study had several limitations. All
participating headache treatment facilities were
located in large urban areas of Ohio. The extent to
which study findings generalize to other geographic
regions is unclear. The current study utilized a selfrecorded daily diary measure of adherence; no objective measures of adherence were used (eg, MEMS or
prescription refills). While daily self-recorded measures can alleviate problems related to retrospective
recall, they are still prone to problems related to
demand characteristics and social desirability and
may overestimate rates of medication adherence.45
This study used a relatively small nonprobability
sample and African American patients were
recruited into the study more aggressively than were
Caucasians (to ensure adequate representation of
African American patients). Because no data were
collected that characterized the demographic compositions of the 4 participating headache subspecialty
clinics, it was not possible to determine if patients
enrolled in the study were representative of the
clinics from which they were recruited. Finally, while
patients who provided adherence data did not differ
from those who did not provide adherence data,
study findings are likely to generalize slightly more so
to Caucasian patients who are female, older, less educated, more likely to be depressed, and have headaches that are more frequent, severe, and disabling
and African American patients who are female and
529
poorer (given patterns of attrition from baseline to
6-month follow-up).
An important limitation that warrants reiteration
is that adherence was assessed only once and near the
completion of the study’s final follow-up period.
Patients who dropped out of the study may have evidenced different (and potentially lower) rates of
adherence than patients who remained in the study,
further limiting the generalizability of study findings.
As such, it is likely that this study characterized and
modeled medication adherence in relatively adherent
headache patients, limiting the external validity of
study findings. Additionally, some patients may have
been managing their headaches during the study
through relaxation, meditation, biofeedback, and
herbal therapies. While practices such as these may
have altered patients’ headache activity and adherence to pharmacotherapies, they were not assessed in
the study. Measures used in the current study were
not specific to medication adherence behaviors and
beliefs. For example, the self-efficacy measure
assessed patients’ abilities to manage their headaches
and was not specific to medication adherence selfefficacy. The relationship between self-efficacy and
preventive medication adherence might have differed
if a medication-specific measure of self-efficacy was
used. The relatively small number of patients enrolled
in the study did not permit us to examine if race
differences existed in adherence to different classes of
preventive medications, such as antidepressants, anticonvulsants, or b-blockers. Finally, study findings generalize only to headache patients being treated in
headache subspecialty clinics (not patients with headaches in primary care settings, etc).
CONCLUSIONS
In spite of these limitations, this study is perhaps
the first to investigate race-related differences in rates
and predictors of adherence to preventive pharmacotherapies. This research found that while African
American and Caucasian patients did not differ significantly in adherence to preventive headache
agents, almost one-third of African Americans failed
to achieve the 80% adherence rate recommended for
persons taking medications for chronic health conditions. Research on rates and predictors of medication
530
adherence in chronic health conditions such as HIV/
AIDS, diabetes, and hypertension is extensive and
rather sophisticated (eg, the use of MEMS caps and
pharmacy refills to assess adherence and studies correlating different types of adherence assessment
methodologies to clinical health outcomes). Far less
research has examined medication adherence and
how medication adherence relates to treatment outcomes in persons with headache disorders. While the
limitations associated with this exploratory study
prevent us from making any definitive conclusions
regarding how medication adherence differs by race
in headache patients, perhaps this study can serve as a
starting point from which additional and more rigorous scientific studies of medication adherence in
headache patients can be initiated. Medication adherence research in the area of headache appears to be
lagging in amount, sophistication, and theoretical
rigor relative to this type of research in other chronic
health conditions. It is time to narrow the research
gap on this important topic.
Acknowledgments: This research was supported by
Grant K01 NS046582 from the National Institute of Neurological Disorders and Stroke (B. Heckman, P.I.). We
would like to acknowledge our collaborators Dr. Ken
Holroyd and the Project INSIGHT Research Team for
their helpful comments on the manuscript and for their
important contributions to the conduct of the study.
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