HIV Antiretroviral Treatment Adherence and Its Impact on HIV Disease Indicators in the US Military HIV Natural History Cohort Study

Background: Treatment or medication adherence is an important factor in improving HIV disease indicators among HIV-infected patients. Among members of the US Military HIV Natural History Cohort Study (NHS), we compared self-report and pharmacy-based refill adherence measures and evaluated their association to HIV disease indicators (HIV RNA viral load and CD4 counts).;Methods: Self-report adherence data was retrieved for 1572 individuals from the NHS cohort during 2006-2010 while pharmacy-based refill data was collected from 2005-2009 for 1458 NHS study participants to create pharmacy-based refill adherence measures (proportion of days covered). Adherence measures and repeated measures of HIV RNA viral load and CD4 counts were analyzed using a mixed effect model to evaluate whether antiretroviral adherence impacted disease progression in this cohort. Race/ethnicity and depressive symptoms (CESD =16) were included in the final model to assess their respective mediating effects on antiretroviral adherence and HIV disease indicators. Self-report and pharmacy-based refill adherence measures were compared using Cohen's Kappa. Chi Square test was administered to detect differences in responses between African Americans (AA) and European Americans (EA) for reasons for missed doses (barriers to treatment adherence).;Results: Level of agreement in identifying optimal adherers (>=90%) was low between self-report and pharmacy-based refill measures (Cohen's Kappa: 0.05). Using self-report adherence in the mixed effects models resulted in a decrease of 0.14 log viral load and an increase of 8.8 cells/mm3 CD4 count for every 10% increase in adherence. Pharmacy-based refill adherence was not associated with HIV RNA viral load. Race/ethnicity was an independent predictor for viral load with AA having an increase of 0.09 log viral load compared to EA keeping other covariates constant. Depressive symptoms were not significantly associated with HIV RNA viral load after adjustment. Chi square tests were significant in detecting race differences (between AA and EA) for the majority of reasons for missed doses (barriers to adherence).;Conclusions: Self-reported adherence was significantly associated with HIV RNA viral load and CD4 counts. The mediating effect of race (AA) was significant in evaluating the association between treatment adherence and HIV RNA viral load. AA reported more barriers to treatment adherence in comparison to EA in this cohort.