BACKGROUND
Evidence is conflicting about the association of abacavir use and cardiovascular disease (CVD) among HIV-infected individuals. Previous studies may have been biased by the preferential initiation or continuation of abacavir in patients with renal dysfunction.
METHODS
We conducted a cohort study in Kaiser Permanente California during 1998-2011, following HIV-infected adults initiating antiretroviral therapy until the earliest of CVD (ie, coronary heart disease or ischemic stroke), health plan disenrollment, death, or end of study. We used inverse-probability weighting to fit marginal structural models to estimate hazard ratios (HRs) for CVD comparing regimens with and without abacavir. Propensity score models included demographics, HIV-specific factors, and CVD risk factors, including alcohol/drug use, smoking, overweight/obesity, diabetes, lipid-lowering and hypertension therapy, and renal dysfunction (ie, estimated glomerular filtration rate <60 mL·min·1.73 m).
RESULTS
Among 8154 subjects, 178 had ≥1 CVD event, with 24/704 (3.4%) in the abacavir group and 154/7450 (2.1%) in the group initiating regimens without abacavir. Abacavir users had more renal dysfunction at antiretroviral therapy initiation (7.0% vs. 3.3%, P < 0.001). Compared with patients initiating regimens without abacavir, abacavir users had a 2.2-fold higher risk of CVD in intention-to-treat analysis [HR 2.2, 95% confidence interval (CI): 1.4 to 3.5], a 2.7-fold higher risk when remaining on their initial regimens for ≥1 year (HR 2.7, 95% CI: 1.5 to 5.0), and a 2.1-fold higher risk in per-protocol analysis (HR 2.1, 95% CI: 0.9 to 5.0).
CONCLUSIONS
Abacavir was associated with an over 2-fold increased risk of CVD, which was not explained by renal dysfunction or other CVD risk factors.