2008. Medication Adherence as a Predictor of Outcomes in HIV-Infected Men
Abraham Hartzema, PhD, MSPH, Department of Pharmacy Health Care Administration, College of Pharamacy, University of Florida, C Uphold, Veterans Affairs Rehabilitation Outcomes Research Center, Gainesvile VAMC, S Kwon,
Department of Pharmacy Health Care Administration, College of Pharamacy, University of Florida, K Sinha,
Department of Biostatistics, University of Florida
Objectives: To describe adherence rates of HIV-infected patients and to examine the validity of two measures of adherence in predicting therapy outcomes.
Methods: Data from a longitudinal cohort of 122 veterans were analyzed at baseline. Complete data on both self-reported adherence and refill rate was established for 111 subjects. Administrative refill histories were abstracted from the Veterans Affairs Pharmacy Benefit Management database October 1999-Oct 2002. Self-report adherence was measured by the Patient Medication Adherence Questionnaire 7. CD4+ cells and viral loads were abstracted from the medical records.
Results: The average refill rate was 82%. 31 % of enrollees had =95% refill rate. Self-reported compliance ranged from 0% to 100%. The Spearman correlation coefficient between self reported adherence and refill adherence rate was 0.15 (p=.1158). Spearman correlation coefficients between CD4+cells, viral load and refill rates were 0.23 (p=0.011) and -0.176 (p=0.05), respectively. The correlation coefficient between CD4+ cell counts, viral load and self-reported adherence were 0.052 (p=0.59) and -0.016 (p=0.87), respectively.
Conclusions: Medication adherence is a highly important determinant of improving immunity (CD4+ cells) and decreasing viral loads. Refill rate is a better predictor of outcomes then patientsí self report. National guidelines recommend that at least 95% of antiretroviral medications must be taken for therapy to be effective and to avoid drug resistance. Only 27% of the patients met this criterion.
Impact: Our findings highlight the importance of assessing adherence by reviewing refill history rather than relying on patientsí self-report. Continuing efforts and resources are needed to improve adherence rates.