Predictors of medication adherence in an AIDS clinical trial: patient and clinician perceptions.
Abstract: This article presents data from an AIDS clinical trial that evaluated 238 (60 percent nonwhite) patients infected with HIV and their clinician's perceptions of medication adherence and visit attendance in relationship to lifestyle, psychosocial, and health belief model (HBM) variables. Twelve sites collected data via a prospective, multisite observational study design involving a companion study to a larger randomized clinical trial. Baseline information was collected by questionnaire and patient self-report on lifestyle; work and health-care experiences; available support; and psychosocial issues, including the HBM constructs. At follow-up visits, clinicians and patients graded medication adherence using the same scale. Patients confidentially reported follow-up information about lifestyle and answered HBM questions. After 12 months, adherence with study visits was associated with older age. Clinicians rated patients as having good adherence significantly more often when those patients were older, were employed at the time of enrollment, exhibited altruism as part of the reason for enrolling in the clinical trial, and thought HIV was very serious. Patients rated themselves as having good adherence significantly more often if they were older, had family or friends who were infected with HIV, and believed that being in the study was worth the trouble.

KEY WORDS: adherence; clinical trials; compliance; health belief model; HIV/AIDS
Article Type: Clinical report
Subject: HIV patients (Drug therapy)
AIDS (Disease) (Care and treatment)
Patient compliance (Research)
Author: Cox, Lisa E.
Pub Date: 11/01/2009
Publication: Name: Health and Social Work Publisher: National Association of Social Workers Audience: Academic; Professional Format: Magazine/Journal Subject: Health; Sociology and social work Copyright: COPYRIGHT 2009 National Association of Social Workers ISSN: 0360-7283
Issue: Date: Nov, 2009 Source Volume: 34 Source Issue: 4
Topic: Event Code: 310 Science & research
Geographic: Geographic Scope: United States Geographic Code: 1USA United States
Accession Number: 212105903
Full Text: In phase I and phase II trials with participants who have HIV, close monitoring of medication adherence is usually part of the study design. In phase III trials, however, medication and appointment adherence may not be as tightly monitored or reported, and thus the extent of nonadherence is often unaccounted for in the analyses and interpretations of these clinical trials (Boudes, 1998; Freedman, 1990). Such distinctions are relevant to social workers, who either help researchers design clinical trims or help clients enroll in them. Social workers are reservoirs of information, conduits of retention, and problem solvers who facilitate the doctor-patient relationship when clinical trial management is involved (Cox, 2002; Williams, 1999).

As a result of medical advances in the management of HIV, individuals who are infected are required to adhere to complicated regimens involving three or more medications, some with multiple doses per day. This contributes to the likelihood that patients will have difficulty following their regimens. Failure to take medications properly can result in the development of HIV resistance, posing a threat to the individual infected with HIV and to those to whom a resistant virus could be transmitted. Thus, it is imperative to elucidate the factors affecting medication adherence of patients who are infected with HIV; therefore, a major thrust of the present study was to reveal these medication compliance predictors.

The majority of studies evaluating medication adherence in patients with chronic illnesses such as hypertension, epilepsy, heart disease, or diabetes have demonstrated adherence rates of 50 percent or less among patients treated for these incurable but not necessarily fatal diseases (Kravitz et al., 1993; Sackett & Snow, 1979). Several reviews have provided extensive summaries of the existing general an d HIV-related adherence research literature (Besch, 1995; Ickovis & Weisler, 1997; O'Brien, Petrie, & Raeburn, 1992). Common nonadherent behaviors include discontinuing treatment prematurely, taking medications incorrectly, taking drug holidays, using treatments or substances not prescribed, and not attending appointments. Low adherence levels in a clinical trial may result in erroneous conclusions if participant adherence is not taken into account when the results are interpreted (Horowitz & Horowitz, 1993).

At the time of the design of the present adherence study--a companion to a clinical trial being conducted by a federally funded, community-based program--the only published study designed to assess the primary sociocultural determinants of HIV patient adherence within an experimental phase III research drug study had been conducted by Morse et al. (1991).The Morse et al. study used nurses' ratings of patients' medication adherence for ACTG 019, a double-blind, placebo-controlled trial of zidovudine in asymptomatic individuals with HIV. This study of mostly gay white men found that the more adherent patients lived farther from their study site; were less concerned with confidentiality; and were more likely to have emotional, economic, and social support.

The present adherence study's parent clinical trials program developed an observational adherence protocol to systematically evaluate the differential patterns of adherence with taking two different regimens of Bactrim to prevent an often-fatal HIV-related opportunistic infection. For five years, the adherence study evaluated patient and clinician perceptions of adherence with protocol-specific pill-taking regimens and study visit attendance in relationship to psychological variables and health belief model (HBM) premises.

METHOD

Study Population

To be eligible for the adherence study, patients had to be enrolled in the Pneumocystis carinii pneumoni (PCP) prophylaxis trial (PCP-TMS study) (El-Sadr et al., 1999) and be able to read English or Spanish. The PCP-TMS study compared daily double-strength trimethoprim-sulfamethoxazole (TMS) to thrice-weekly TMS for prevention or primary or secondary PCP in study patients with a CD4 cell count of less than 200 cell/[mm.sup.3]. At the 12 participating Community Programs for Clinical Research on AIDS (CPCRA) sites, enrollment in the adherence study was offered to patients as they were enrolled in the PCP-TMS study, but participation in the adherence study was not mandatory, producing a self-selected study population.

Study Design and Data Collection Tools

The adherence study was designed as a prospective, multisite, multimeasure observational study. Behavior was examined through semistructured patient interviews, clinical assessment, and a self-administered questionnaire. Follow-up measures were obtained every four months. At enrollment, trained research personnel administered a baseline data questionnaire. The baseline questionnaire gathered information regarding demographic variables, socioeconomic status, lifestyle habits, living arrangements, and forms of support available to patients in addition to responses to questions about clinical trials and HIV infection based on the HBM. The HBM posits that patients weigh the following factors in deciding to follow medical advice:perceived susceptibility to and severity of disease, barriers to treatment, and benefits of the recommended treatment. At scheduled follow-up visits, patient adherence with Bactrim, the study medicine for the parent PCP-TMS study, was determined by self-report and clinician ratings. Both patients and clinicians responded to the same three-point Likert-type scale, rating medication adherence behavior as good (patient took at least 80 percent of study medications), fair (patient took 50 percent to 79 percent), or poor (patient took less than 50 percent).

For the adherence study, patients were defined as having good medication adherence if they and their clinicians judged that they took at least 80 percent of the prescribed study medication (Bactrim) and as being nonadherent if they took less than 80 percent of their medication, corresponding to the fair and poor categories outlined for the parent study. Adherence with study visits was defined as patients being seen at any time within the two- to four-month study window defined by the PCP-TMS study. Patients were considered to have missed a visit if they did not attend the clinic so that a clinician could assess them. Adherence study participants who had their PCP-TMS study Bactrim discontinued were no longer assessed for adherence.

A patient self-report form--which captured information about lifestyle, patients' perceptions of their health-care providers, barriers to adhering to protocol requirements, and HBM premises--was completed at regular intervals. There were no personal identifiers on the self-report forms, and patients completed their forms in private and then mailed them directly to the CPCRA Statistical Center at the University of Minnesota. This procedure was adopted to allow the patients confidentiality in responding to questions evaluating their health-care providers. All questionnaires used were modified versions of interview schedules originally used by Morse et al. (1991).

Statistical Analysis

Summary statistics for the baseline variables were calculated. Frequency distributions of the responses to each statement of the HBM were prepared. These responses were graphed into two categories: (1) neutral, agree, or strongly agree, which defines the case of the patient agreeing with the statement; and (2) strongly disagree or disagree, which defines the case of the patient disagreeing with the statement. Compliance at each follow-up visit at which study drugs were prescribed was coded as good or not good for both patient- and clinician-assessed compliance. Attendance at each follow-up visit was coded as attended or not attended. The percentages of patients classified as good compilers by patient and clinician were determined for selected variables, including possible responses to the HBM. Extensions of the logistic regression model for longitudinal data, generalized estimating equations (Diggle, Liang, & Zegers, 1994) were used to determine which variables were predictive of good compliance as assessed by the patient, good compliance as assessed by the clinician, and visit attendance. A two-step procedure was used to determine which variables to include in the final models. First, univariate models were run to select variables that were predictive at the [alpha] = .05 level. For the models predicting good compliance, variables that were predictive of either patient- or clinician-assessed compliance in at least one of the two models were included, regardless of their significance level. Their inclusion provides some data concerning the strength or weakness of the findings of those odds ratios.

RESULTS

From the PCP-TMS study, 378 of 2,625 total participants (14 percent) co-enrolled in the adherence study and completed the baseline data form. Baseline characteristics of the study population are shown in Table 1. The adherence study cohort differed significantly from the entire PCP-TMS cohort in two respects: The adherence cohort contained fewer Latinos--Hispanics (9 percent versus 14 percent), and more adherence study patients were taking antiretroviral therapy at baseline (79.4 percent versus 65.8 percent).

The demographic profile of the population in the PCP-TMS study shows that a majority of patients (60 percent) were people of color, predominantly African American; over 75 percent had at least a high school education; 38 percent were employed at the time of enrollment; and over 50 percent had used street drugs other than marijuana. Patient CD4 cell counts were less than 200, as required for enrollment in the PCP-TMS protocol.

Five questions based on the HBM were asked to determine patients' perceptions about participation in the PCP-TMS protocol. The results are shown in Table 2. Most (94 percent) agreed that being infected with HIV was very serious, and just over half thought AIDS was the worst disease one could get. A small percentage (less than 1 percent) agreed that being in the PCP-TMS study was more trouble than it was worth. Responses to the question addressing the personal health benefit of participating in a medication research study--"participating in a medication research study will prevent me from getting sicker"--were evenly distributed among those who agreed, were neutral, or disagreed.

Ratings of medication adherence by study patients and clinicians, along with attendance at follow-up visits, for selected baseline characteristics are shown in Table 3. In general, patients rated themselves as less adherent than did clinicians, and those who were in the youngest age group, had the least education, had used street drugs other than marijuana, and felt that their participation would not benefit the health of other people or that being in the study was more trouble than it was worth gave themselves the lowest adherence ratings. Clinicians gave the lowest adherence ratings to patients who felt participation would not help others, those who felt study participation was more trouble than it was worth, and those with the least education.

Adherence with Attendance at Study Visits

Using a very limited operational definition of visit attendance, it is seen that the mean number of missed visits for all study patients was 10 percent, ranging from 0 percent to 24.7 percent among the clinical trial units. Multivariate analysis (see Table 4) revealed that of the 41 baseline characteristics assessed, three were associated with visit adherence. Treatment assignment (daily versus thrice-weekly TMS) and older age were analyzed in 10-year increments and included those patients who chose to be in the study because of altruism. Previous incarceration was associated with missing follow-up visits.

Medication Adherence

The results of a multivariate analysis of baseline variables associated with medication adherence ratings by clinicians and patients for the PCP-TMS cohort are presented in Table 5. Treatment regimen (that is, daily versus thrice-weekly TMS assignment) was not related to adherence assessments. Clinician and patient assessments of medication adherence were compared at six and 12 months. At six months, 92 percent of patients were rated as having good adherence by clinicians, whereas 87 percent were rated as having good adherence by self-assessment ([kappa] = .251). At 12 months, the clinician and patient ratings for good medication adherence were 92 percent and 83 percent, respectively ([kappa] = .90).

Baseline characteristics significantly associated with a clinician rating of good medication adherence included older age, being employed at time of enrollment into the study, and choosing to participate in clinical trials because the information gained might help others. Baseline characteristics associated with poor adherence ratings were nonwhite ethnicity, use of illegal street drugs other than marijuana, and relating an attitude that AIDS is the worst disease one can get.

Patients' self-reported ratings of good medication adherence were statistically significant when associated with older age (as measured in five-year increments). Having family or friends infected with HIV was statistically significant when associated with good medication adherence for the PCP-TMS cohort. Being nonwhite and using street drugs other than marijuana were associated with self-reported poor adherence.

DISCUSSION

Baseline characteristics of clinical trial study patients that predicted either clinician- or patient-rated medication adherence included older age, an altruistic attitude, and social stability suggested by employment. Baseline characteristics associated with nonadherence included lack of social stability (for example, use of illegal drugs), being unemployed, and being less educated. The statistically significant baseline characteristics associated with missing study visits were the treatment assignment (daily versus thrice-weekly TMS), younger age, and altruistic motivation. These results are similar to the findings of previous adherence studies of other chronic diseases, in which adherence to medical treatment was influenced by psychopathology, social isolation, actual or perceived adverse medication effect, and treatments requiring behavioral change (Becker & Maiman, 1975; Blackwell, 1973; Griffith, 1990; Haynes, 1976).

Overall, patients in the adherence cohort of the PCP-TMS study were rated as having good medication adherence 86 percent of the time by clinicians and 70 percent of the time by their own self-assessment. The high rates of self-reported medication adherence, if accurate, may reflect the pill-taking behavior of individuals who choose to participant in research trials such as the present study. The findings of this study are strengthened by the agreement between the independent adherence assessments of patients and clinicians. However, there are several limitations and potential sources of sampling bias in the companion study. First, individuals who chose to participate in the parent PCP-TMS trial and the adherence study may differ from the at-large population of individuals who are infected with HIV. The small number of patients from the parent study who enrolled in the adherence study may not be representative of the PCP-TMS study cohort given that comparable information on social support, HBM constructs, mental illness, and incarceration was not collected for the parent study. In addition, the attention given to adherence in these studies may have produced a Hawthorne effect, inadvertently increasing medication adherence. Finally, though, agreement between clinicians and patients about predictors for good and not good adherence lends strength to the observational findings. Conclusions that can be drawn from this study are limited by the lack of an objective measure of adherence, though the adherence literature--especially in the field of HIV-related medication adherence--strongly supports the validity of self-reported measures of patient adherence.

Three studies on adherence to medicines for prophylaxis of opportunistic infections in HIV-infected individuals have been reported in the literature (Eldred, Wu, Chiasson, & Moore, 1998; Pekovic et al., 1998; Zachariah et al., 2001) and included evaluation of patients taking isoniazid (INH), cotrimoxazole, and various PCP prophylaxis regimens. Two of these studies are comparable in study design and size to the present adherence study.

Treatment of 2,960 Ugandans, 92 percent of whom were infected with HIV, at high risk for tuberculosis using three short-course (three- to six-month) prophylactic medication regimens was undertaken in a randomized, placebo-controlled but no-blind study (Pekovic et al., 1998). Criteria for enrollment included having a positive or anergic tuberculin skin test response, living within 20 kilometers of the project site, and willingness to be followed. Adherence was measured by testing urine for presence of INH metabolites, attendance at monthly follow-up appointments, and self-report. A compliance questionnaire given to patients at the one- and three-month visits gathered information on knowledge of regimen and amount of medication taken. During the study, home visits were made by staff trained in motivational techniques to patients who missed appointments or had negative results on the INH urine test. Analyses were done on the individual measures and on combinations of the measures after development of composite indices using all three assessment methods, resulting in a score for each patient. Eighty-six patients attended at least two-thirds of scheduled study visits. Overall, though knowledge of the regimen and dosing was high (greater than 90 percent), 30 percent of all patients reported forgetting to take some of their medication. Of the total number of urine samples tested for INH, 77 percent were positive. Analysis of individual measures of adherence showed that correlations among them were weak, that each measure provided information on a different aspect of adherence, and that they were not redundant.

Consistently across all analyses, knowledge of the regimen and features of the study arm were independently associated with adherence. The characteristics that were associated with better adherence included being older, having a better knowledge of the medication regimen, not having a military occupation, being on the simplest regimen (fewest number of pills), being skin-test positive, and having a reason for enrollment other than just to learn one's tuberculosis or HIV status.

Some of the results of the present adherence study echoed these findings in that the more adherent patients were older, and their motivation for entering into the study appeared related to later adherence. Patients who entered the Ugandan INH prophylaxis trial to resolve their personal concerns about their tuberculosis or HIV status had significantly lower scores on all composite indices than did patients who stated other reasons for participation.

A large study of adherence to PCP prophylaxis was performed at the Johns Hopkins Hospital HIV Clinic before the advent of effective combination therapy (Eldred et al., 1998). Potential study participants were recruited from a group of patients considered to be engaged in care (at least one clinic visit in the previous six months) and who had already been on antiretroviral medicines for at least six months. Eighty-five percent of the study cohort were African American, 63 percent were male, 54 percent had injecting drug use as an HIV risk factor, and 69 percent had CD4 cell counts under 200/[mm.sup.3]. Medication adherence was measured by self-report of total dose of medication taken over the previous seven days and total number of days in the previous two weeks on which medication was taken. Medical records were reviewed to derive the proportion of pills taken (number taken divided by number prescribed). To verify self-report, a urinary test for unconjugated sulfamethoxazole was performed using mass spectophotometry in a subset of those prescribed TMS who reported taking TMS in the previous three days. Adherence to pentamidine was assessed by chart review. Adherence of more than 80 percent was considered acceptable, based on previous data from studies of the treatment of latent tuberculosis.

Sixty percent of study patients took at least 80 percent of their antiretroviral medicines, and 49 percent took at least 80 percent of their prescribed PCP prophylaxis medicines. Of those reporting adherence to TMS, 70 percent had detectable urinary sulfamethoxazole, meaning they had taken this medicine within the previous 48 hours. Reasons for not taking medicines included forgetfulness (30 percent), fear of side effects (26 percent), and drug or alcohol use (16 percent).

Sociodemographic characteristics and number of prescribed medicines were not associated with either PCP or antiretroviral adherence. Associated with adherence to PCP prophylaxis by self-report and review of medical records were likelihood of taking medicines away from home, positive self-efficacy (belief in ability to adhere to therapy), presence of family, ability to afford medication copayments, and higher scores on mental health testing. Injecting drug use was associated with poor adherence to taking PCP prophylaxis therapy in multivariate analysis.

The present adherence study differed in several respects from the Johns Hopkins study. Demographically, there were fewer women, injecting drug users, and minorities in the non-Hopkins study cohort. Patients who were recruited in this cohort also included those new to HIV care and established patients. In the adherence study, information was collected on education as a surrogate for socioeconomic status, and as 20 percent were college graduates, study patients were from potentially more diverse socioeconomic backgrounds. The sample size for study patients taking TMS for PCP prophylaxis was smaller (N = 135) in the Hopkins cohort than in federally funded cohort (N = 378).

Despite these differences, the types of characteristics predictive of adherence during follow-up are confirmatory of observed data trends. These include enhancement of the social stability of patients infected with HIV by involving family or friends; provision of alcohol and substance abuse treatment programs in primary care settings; maximum use of available support from social service agencies; and, for the young, continued focused educational efforts on the course of HIV infection and its treatment. More marginal patients tend to be less adherent to medications and visits and, thus, may require research sites to invest more resources in them to maintain adherence. One final noteworthy finding is that doctors and patients were in relatively high agreement with regard to accessing perceived patterns of medication adherence.

Original manuscript received January 3, 2008

Final revision received August 7, 2008

Accepted December 3, 2008

REFERENCES

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Besch, C. L. (1995). Compliance in clinical trials. Journal of Acquired Immune Deficiency Syndrome, 9, 1-10.

Blackwell, B. (1973). Drug therapy: Patient compliance. New England Journal of Medicine, 289, 249-252.

Boudes, P. (1998). Drug compliance in therapeutic trials: A review. Controlled Clinical Trials, 19, 257-268.

Cox, L. (2002). Social support, medication compliance and HIV/AIDS. Social Work in Health Care, 35, 425-460.

Diggle, R, Liang, K., & Zegers, P. (1994). Analysis of longitudinal data. Oxford, England: Clarendon Press.

Eldred, L., Wu, A.W., Chiasson, R.E., & Moore, D. (1998). Adherence to antiretroviral and pneumocystis prophylaxis in HIV disease. Journal of Acquired Immune Deficiency Syndrome and Human Retrovirology, 18, 117-125.

El-Sadr, W. M., Luskin-Hawk, R., Yurik, T. M., Walker, J., Abrams, D., John, S. L., et al. (1999). A randomized trial of daily and thrice-weekly trimethoprim-sulfamethoxazole for the prevention of Pneumocystis carinii pneuomonia in human immunodeficiency virus-infected persons. Clinical Infectious Diseases, 29, 775-783.

Freedman, L. S. (1990). The effect of partial noncompliance on the power of a clinical trial. Controlled Clinical Trials, 11, 157-168.

Griffith, S. (1990). A review of the factors associated with patient compliance and the taking of prescribed medications. British Journal of General Practice, 40, 114-116.

Haynes, P,. B. (1976). A critical review of the "determinants" of patient compliance with therapeutic regimens. In D. L. Sackett & R. B. Haynes (Eds.), Compliance with therapeutic regimens (pp. 26-39). Baltimore: Johns Hopkins University Press.

Horowitz, R. I., & Horowitz, S. M. (1993). Adherence to treatment and health outcomes. Archives of Internal Medicine, 153, 1863-1868.

Ickovis, J. R., & Weisler, A.W. (1997). Adherence in AIDS clinical trials: A framework for clinical research and clinical care. Journal of Clinical Epidemiology, 50, 385-391.

Kravitz, R. L., Hays, R. D., Sherbourne, C. D., DiMatteo, M. R., Rogers, W. H., Ordway, L., & Greenfield, S. (1993). Recall of recommendations and adherence to advice among patients with chronic medical conditions. Archives of Internal Medicine, 153, 1869-1878.

Morse, E.V., Simon, P. M., Coburn, M., Hyslop, N., Greenspan, D., & Balson, P. M. (1991). Determinants of subject compliance within an experimental anti-HIV drug protocol. Social Science and Medicine, 32, 1161-1167.

O'Brien, M. K., Petrie, R., & Raeburn, J. (1992). Adherence to medication regimens: Updating a complex medical issue. Medical Care Review, 49, 435-454.

Pekovic, V., Mayanja, H., Vjecha, M., Johnson, J., Okwera, A., Nsubuga, P., et al. (1998). Comparison of three composite compliance indices in a trial of self-administered preventive therapy for tuberculosis in HIV-infected Ugandan adults. Journal of Clinical Epidemiology, 51, 597-607.

Sackett, D. L., & Snow, J. C. (1979). The magnitude of compliance and non-compliance. In R. B. Haynes, D. Taylor, & D. L. Sackett (Eds.), Compliance in health care (pp. 11-22). Baltimore: Johns Hopkins University Press.

Williams, J. (1999).The role of social work in HIV/AIDS clinical trials. Social Work in Health Care, 29, 35-56.

Zachariah, R., Harries, A.D., Arendt,V., Wenning, R, Schneider, S., Spielmann, M., et al. (2001). Compliance with cotrimoxazole prophylaxis for the prevention of opportunistic infections in HIV-positive tuberculosis patients in Thyolo district, Malawi. International Journal of Tuberculosis Lung Disorders, 5, 843-846.

Lisa E. Cox, PhD, LCSW, MSW, is associate professor, School of Social and Behavioral Sciences, Richard Stockton College of New Jersey, P.O. Box 195, Jimmie Leeds Road, Pomona, NJ 08240; e-mail: lisa.cox@stockton.edu. This article was assembled with the use of data provided by the Terry Beirn Community Programs for Clinical Research on AIDS (CPCRA) (National Institutes of Health, National Institute of Allergies and Infectious Diseases, Contract Numbers Y01-AI-0002, Y01-A1-4040, and Y1-AI-0431), and the author thanks the CPCRA for its early support and willingness to share data from the CPCRA 012 and CPCRA 006 studies. In addition, gratitude and acknowledgement goes to the following original CPCRA units and members for their intellectual, statistical, and writing and editing contributions: C. Lynn Besch, MD, Glenn Bartsch, PhD, Carroll Child, PhD, Donald L Abrams, MD, the CPCRA Richmond AIDS Consortium clinical trials unit, and Betsy Finley, RN
Table 1: Summary Statistics of
Selected Patient (N = 378)
Characteristics at Baseline

Variable                                M(SD)         %

Age (years)                             39.0 (8.8)
Female                                               13.0
Nonwhite                                             60.3
History of prior injecting drug use                  29.6
CD4 cell count (cells/mm3)                           69.0
Prior AIDS diagnosis                                 36.2
Education
  Less than high school                              21.8
  High school graduate                               58.1
  College graduate                                   20.2
Currently employed                                   37.7
Chose to take part in the study to
     help other people                               62.3
Prior use of street drugs other than
     marijuana                                       52.2

Note: One patient had missing data for the variables indicated

Table 2: Frequency Distribution of Responses to Health
Belief Model Statements at Baseline

                                          Strongly
                                          Disagree      Disagree
Health Belief                Number
Model Statement            Responding     n      %      n       %

Being infected with HIV
  is very serious.            377          6    1.6      4    1.1
AIDS is the worst
  disease you can get.        377         17    4.5     46   12.2
Participating in a
  medication research
  study will prevent
  me from getting sicker      376         42   11.2     89   23.7
Participating in a
  medication research
  study will benefit
  the health of other
  people.                     377          2    0.5      2    0.5
Participating in a
  medication research
  study is more trouble
  than it's worth.            376        151   40.2    168   44.7

Health Belief
Model Statement
                            Neutral       Agree

                            n      %     n     %
Being infected with HIV
  is very serious.          13    3.4   65   17.0
AIDS is the worst
  disease you can get.      72   19.1   84   22.0
Participating in a
  medication research
  study will prevent
  me from getting sicker   115   30.6   79   21.0
Participating in a
  medication research
  study will benefit
  the health of other
  people.                   25    6.6   17   47.0
Participating in a
  medication research
  study is more trouble
  than it's worth.          47   12.5    6    1.0

Table 3: Frequency of Reporting Good Medication Adherence
or Attendance at Follow-up Visits by Level of Selected
Baseline Characteristics

                                Visits at Which
                                Bactrim Adherence
                                Was Rated Good (%)

                                  By         By
Characteristic             n    Patient   Clinician

Randomized treatment
assignment (dosing
schedule)
  Daily                   189    78.7        85
  3x/week                 189    79.1        86
  Total                   378
Age (years)
  <35                     115    71.5        80
  35-45                   185    80.0        86
  >45                     78     85.1        89
  Total                   378
Nonwhite
  Yes                     228    71.5        82
  No                      150    88.5        89
  Total                   377
Education
  Less than high school   82     64.1        77
  High school             219    80.7        86
  College graduate        76     87.7        92
  Total                   377
Currently employed
  Yes                     142    82.6        90
  No                      235    76.1        82
  Total                   377
Chose to participate
in the study to help
other people
  Yes                     256    80.1        89
  No                      11     77.3        78
  Total                   377
Ever used street drugs
(other than marijuana)
  Yes                     197    72.9        81
  Total                   377

Note: Yes = response of neutral, agree, or strongly
agree; No = response of strongly disagree or disagree.

Table 4: Baseline Characteristics Associated with Visit
Adherence from the Generalized Logistic Regression Revealing
the Odds Ratios of Good versus Not Good Parent Study Cohort
Adherence at Follow-up Visits

                               Assessed by Patient

Characteristic                  OR (95% CI)       p

Age (10-year increment)        2.1 (1.5. 3.1)   .0001
Nonwhite                       0.3 (0.2, 0.7)   .002
Currently employed             0.9 (0.5, 1.8)   .81
Education (4-year increment)   2.6 (1.4, 4.9)   .002
Chose to be in the study to
  help others                  1.1 (0.6, 2.0)   .80
Prior use of street drugs
  (other than marijuana)       0.5 (0.3, 0.9)   .014
Agrees that being infected
  with HIV is very serious     1.4 (0.4, 5.4)   .61
Agrees that AIDS is the
  worst disease you can get    1.2 (0.6, 2.4)   .58

                               Assessed by Clinician

Characteristic                  OR (95% CI)       p

Age (10-year increment)        1.5 (1.1, 2.0)   .005
Nonwhite                       0.7 (0.4, 1.2)   .21
Currently employed             2.0 (1.1, 3.5)   .013
Education (4-year increment)   1.4 (0.9, 2.3)   .17
Chose to be in the study to
  help others                  2.5 (1.5, 4.1)   .0006
Prior use of street drugs
  (other than marijuana)       0.5 (0.3, 0.8)   .005
Agrees that being infected
  with HIV is very serious     2.8 (1.0, 7.6)   .049
Agrees that AIDS is the
  worst disease you can get    0.6 (0.3, 1.0)   .066

Note: Good = 80 percent or greater; Not Good = less than
80 percent; OR = odds ratio; CI = confidence interval.

Table 5: Baseline Characteristics Associated with Medication
Adherence from the Generalized Logistic Regression Revealing
the Odds Ratios of Good versus Not Good Patient Adherence at
Follow-up Visits

Characteristic                 OR (95% CI)        p

Treatment assignment
  (daily versus
  thrice-weekly)              0.5 (0.3, 0.9)    .023
Age (l0-year increment)       1.7 (1.2, 2.5)    .003
Agrees that participating
  in a medication research
  study will benefit the
  health of other people      3.2 (1.2, 8.7)    .024

Note: Good = greater than 80 percent; Not Good =less than 80
percent; OR = odds ratio; CI = confidence interval.
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