Relationship Between Single Tablet Antiretroviral Regimen and Adherence to Antiretroviral and Non-Antiretroviral Medications Among Veterans' Affairs Patients with Human Immunodeficiency Virus

Several antiretrovirals (ART) have been coformulated as single tablet regimens (STR). Study objectives were to compare ART and non-ART adherence between STR and multiple tablet regimens (MTR) recipients, determine whether STR independently predicts ART adherence, and determine whether ART adherence influences non-ART adherence. A retrospective cohort study was performed among Upstate New York Veterans' Healthcare Administration (VISN-2) patients from 2000 to 2013. Inclusion criteria were age ≥18 years, human immunodeficiency virus (HIV) infection, receipt of ≥3 ART medications for ≥3 months, and available pharmacy refill records. The two study outcomes were adherence to ART medications and non-ART medications. Adherence was determined with pharmacy refill records that were used to calculate medication possession ratios. Among the 1202 subjects, there were 165 (13.7%) STR and 1037 (86.3%) MTR recipients. Mean ± standard deviation (SD) ART adherence was significantly higher for STR recipients (81.5% ± 15.3%) than MTR recipients (66.1% ± 21.1%), p < 0.001. Use of STR [adjusted odds ratio (aOR): 5.76, 95% confidence interval (CI): 3.84-8.65, p < 0.001] was independently associated with optimal (≥90%) adherence to ART. Mean ± SD non-ART adherence did not differ between STR (78.8% ± 15.6%) and MTR recipients (80.8% ± 16.0%), p = 0.17. Optimal adherence to ART medications (aOR: 2.30, 95% CI: 1.57-3.38, p < 0.001) was independently associated with optimal adherence to non-ART medications. The use of STRs are associated with optimal adherence to ART medications, but not directly associated with adherence to non-ART medications.