Adherence to highly active antiretroviral therapy vs clinical and economic outcomes for Medicaid enrollees with HIV and hepatitis C co-infection

Purpose.  We examined the impact of differences in adherence rates to antiretroviral treatment among HCV co-infected HIV patients enrolled in Medicaid.

Methods.  Analyzed Medicaid claims data from 14 states from 2005-2007, comparing survival and clinical outcomes and cost of treatment for HIV/HCC co-infected patients at different levels of adherence to ARV.

Results: 20.5% patients had prescription refill claims indicating less than 50% adherence to ARV.  There was significant survival benefit demonstrated at each incremental level of adherence to ARV.  Low adherence patients also had higher rates of hospitalization and emergency department visits.  Relative to patients with high (>95%) ART-adherence, those with less than 25% treatment adherence had a greater than 4-fold risk of death.  Mild non-adherence (75-95% adherence) had a 1.58 times higher of death. Non-drug Medicaid expenditures were lower for high adherence patients, but the cost of medications drove total Medicaid expenditures higher for the high-adherence patients.  Cost per quality-adjusted life year (QALY) saved (relative to the <25% low-adherence group ranged from $21,874 for increasing adherence to 25-50% to 37,229 for increasing adherence to 75-95%.  The highest level of adherence ( >95%) was associated with a cost of $66,455 per QALY.

Conclusions: Adherence to ARV for patients with HIV/HCV co-infection is associated with lower adverse clinical outcomes at a Medicaid cost per QALY commensurate with other well-accepted treatment and prevention strategies.  Reducing the cost of effective ARV could substantially lower the cost per QALY associated with increased ART adherence, or even lead to absolute cost savings from increasing adherence.