PURPOSE: Achieving optimal outcomes in the treatment of HIV requires a high, sustained level of medication adherence to antiretroviral therapy (ART). Factors thought to affect treatment adherence include patient characteristics and treatment experience with ART. The objective of this study is to document differences in ART adherence according to patient population (i.e., US commercially insured or Medicaid) and treatment experience (i.e., treatment-naïve or treatment-experienced).
METHODS: Commercially insured and Medicaid patients in the US from the MarketScan claims databases with =2 diagnoses of HIV/AIDS between 6/1/2006 and 12/31/2011 who received an ART prescription between 6/1/2007 and 12/31/2010 were selected for initial study inclusion. For each patient, an index date was designated upon receipt of the initial ART prescription during that time. All patients were required to be =18 years of age on their index date and have =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. Logistic regression models were estimated to assess the relationship between previous treatment exposure and adherence while controlling for demographic and clinical characteristics.
RESULTS: Of the 14,590 commercially insured patients who met inclusion criteria, 42% were treatment-naïve, 58% were treatment-experienced, and 59% achieved =80% adherence. Of the 5,744 Medicaid patients who met inclusion criteria, 31% were treatment-naïve, 69% were treatment-experienced, and 42% achieved =80% adherence. After adjusting for confounders (e.g., baseline demographics and clinical characteristics), treatment-experienced patients were more likely to be adherent than treatment-naïve patients, among commercially insured (odds ratio [OR]=1.30; p=0.0001) and Medicaid patients (OR=2.19; p less than 0.0001).
CONCLUSION: After controlling for potential confounding factors, treatment-experienced patients had better adherence to ART, among commercially insured and Medicaid patients.
