OBJECTIVES: Adherence to antiretrovirals (ARVs) is critical to achieving durable virologic suppression and preventing drug resistance. This study assessed predictors of poor adherence in Medicaid beneficiaries living with HIV initiating ARVs, and compared healthcare resource utilization (HRU) and costs between patients with suboptimal and optimal adherence.

METHODS: Multi-state Medicaid administrative data (05/2012-03/2015) was used to identify adults with HIV-1 who initiated commonly used ARV regimens (index date) and had ≥6 months of observation pre- and post-index. Adherence was measured using proportion of days covered (PDC). A multivariable logistic regression was used to assess risk factors of poor adherence (PDC<80%) at 6 months post-index. HRU and costs were compared between patients with suboptimal (80%≤PDC<95%) and optimal (PDC≥95%) adherence using Poisson and ordinary least square models, respectively, and inverse probability of treatment weighting to control for confounding.

RESULTS: Among the 2,683 patients included, 51% had poor, 19% suboptimal, and 30% optimal adherence. Younger age (odds ratio [OR] vs. patients ≥50 years old=1.58, P=0.002), non-capitated (OR=1.40, P<0.001) or dual Medicaid/Medicare insurance coverage (OR=5.98, P<0.001), no prior ARV treatment (OR=1.98, P<0.001), and asymptomatic HIV (OR=1.37, P<0.001) were associated with higher risk of poor adherence Patients with suboptimal adherence had longer hospital stays (incidence rate ratio [IRR]=1.62, P=0.008), more long-term care admissions (IRR=3.11, P=0.008), higher medical costs (mean monthly cost difference [MMCD]=$339, P<0.001), and higher inpatient costs (MMCD=$259, P<0.001) compared to patients with optimal adherence

CONCLUSIONS: Suboptimal adherence was associated with higher HRU and costs compared with optimal adherence. Poor adherence to ARVs was observed in over half of Medicaid patients. The risk of patients being poorly or suboptimally adherent should be a consideration when selecting an ARV regimen.