Association between pharmacy medication refill-based adherence rates and CD4 count and viral-load responses: A retrospective analysis in treatment-experienced adults with HIV

Background: Current guidelines and most contemporary statements in the literature indicate that, like other medical conditions, HIV infection requires exceptionally high adherence to highly active antiretroviral therapy (HAART) for successful treatment. Objective: This study was conducted to determine the association between pharmacy medication refill rates-a surrogate marker for adherence to HAARTand CD4-count/viral-load responses in patients with HIV. Methods: This retrospective study was conducted at the HIV Clinic, Veterans Affairs Medical Center, Durham, North Carolina. Male and female patients aged >= 18 years with a history of HIV who attended clinic appointments on 3 consecutive clinic days were enrolled. Pharmacy medication refill-based adherence rates over the 6 months before the study were determined by examining electronic pharmacy records. The most recent viral load and the change (Delta) in CD4 count over the past year-surrogate measures of outcome-were also collected from each patient's electronic medical record and compared with refill adherence rates. The incidence of AIDS-related events and past antiretroviral experience were also compared with the ACD4 count and adherence rates. Results: Data from 58 patients were included in the study. Thirty-nine patients were black men; the mean age was 51.5 years. There was a nonsignificant correlation between 6-month pharmacy medication refillbased adherence rates and viral loads (r = 0.10). The relationship between Delta CD4 count and adherence was complex. With adherence rates > 70%, the Delta CD4 count ranged from +414 to -238, with no indication that increasing adherence led to a greater CD4 count increase. The ACD4 count progressively declined with adherence rates <= 70%. Patients' past antiretroviral experience or incidence of AIDS-related events did not significantly affect the distribution of Delta CD4 counts or adherence rates. Conclusion: Based on our results, in patients with pharmacy medication refill-based adherence rates > 70%, there was no significant correlation between adherence rates and Delta CD4 counts or viral-load responses.