Adherence pattern, health care utilization, and virologic outcomes among treatment-naive veteran patients with human immunodeficiency virus Type 1 infection

Many studies have estimated the treatment effect of different antiretroviral therapies (ARTs) on human immunodeficiency virus (HIV) patients™ virologic/immunologic outcomes. However, evidence is lacking on how adherence to ARTs influences treatment effects. The goal of this study is to explore HIV treatment-naïve veterans™ health care utilization and to investigate the effect of early adherence on initial viral suppression by different regimens. A cohort study was conducted on HIV veterans initiating ARTs in 1999-2015. The follow-up time was one year since the first fill of base agent (index date). Patients’ health care utilization during the follow-up as well as the correlations between initial adherence and one-year adherence were estimated. The primary outcome was the first viral suppression occurred within thirty to 60 days since the index date. Multiple imputation was used to impute the missing value of virologic outcomes. The inverse probability of treatment weighting (IPTW) method was applied to estimate the viral suppression rate at each specific adherence category for each regimen category. Marginal structural models (MSMs) with IPTW were used to estimate the risk of viral suppression in lower-adherence categories in comparison to near-perfect adherence level ≥95%. Data showed that all patients had at least one follow-up test or visit in the one year. The mean of initial adherence to the base agent was 0.84â€"0.90, depending on the regimens, with unboosted protease inhibitors (PIs) lowest and integrase inhibitors (INSTIs) highest. The correlations between initial adherence and thereafter one-year proportion of days covered (PDC) were medium, estimated at 0.54â€"0.63. Lower adherence caused lower viral suppression rate, with the association differentiated by the regimen. Patients on INSTIs had the highest viral suppression rate, with patients on PIs having the lowest rate. Regardless of regimens, the viral suppression rate among patients at initial adherence of 75-<95% was not statistically different from patients at adherence of ≥ 95%; however, the differences might be clinically significant. Initial adherence differently influenced the viral suppression rate across different regimens. Regardless of regimen categories, no evidence shows 95% adherence threshold is necessary.