OBJECTIVES: Achieving optimal outcomes in the treatment of HIV requires high, sustained levels of medication adherence to antiretroviral therapy (ART). Across many conditions, suboptimal adherence has been shown to lead to poorer outcomes among patients. This study assessed the extent to which patients diagnosed with HIV are adherent with ART treatment guidelines and to illustrate associations between ART adherence and economic outcomes.
METHODS: Commercially insured and Medicaid patients in the US from MarketScan claims databases with ≥ 2 claims containing an HIV/AIDS diagnosis code between June 1, 2006 and December 31, 2011 who received an ART prescription between June 1, 2007 and December 31, 2010 were selected for initial inclusion. For each patient, the first ART prescription received during that time defined the index date. Patients were ≥ 18 years old on their index date and had ≥ 12 months of continuous health plan enrollment with drug benefits before and after their index date. Adherence was measured by patients’ proportion of days covered (PDC) with a complete ART regimen during the 12-month post-index date period; patients with PDC ≥ 80% were considered adherent. Multivariable models (i.e., generalized linear; Poisson) assessed the relationship between ART adherence and economic outcomes (i.e., costs; number of health care encounters), controlling for demographic and clinical characteristics.
RESULTS: A total of 14,590 commercially insured patients met all inclusion criteria, and 59% were adherent; 5,744 Medicaid patients met all inclusion criteria, and 42% were adherent. After adjusting for confounders, ART adherence was associated with 29% and 31% reductions in non-pharmacy costs (p< 0.0001)), 67% and 80% increases in total pharmacy costs (p< 0.0001), 43% and 49% reductions in hospitalizations (p< 0.0001), and 41% and 26% reductions in emergency department visits (p< 0.0001), among commercially insured and Medicaid patients, respectively.
CONCLUSIONS: This study suggests that ART adherence among commercially insured and Medicaid HIV patients in the US may be suboptimal, and that adherence is associated with improved economic outcomes among these patients.
