Toxicity and clinical outcomes in patients with HIV on zidovudine and tenofovir based regimens: a retrospective cohort study.

BACKGROUND Adverse drug reactions are a major concern with zidovudine/stavudine treatment regimens. The less toxic tenofovir regimen is an alternative, but is seldom considered due to the higher costs. This study compared adverse drug reactions and other clinical outcomes resulting from the use of these two treatment regimens in India. METHODS Baseline, clinical characteristics and follow-up outcomes were collected by chart reviews of HIV-positive adults and compared using univariate/multivariate analysis, with and without propensity score adjustments. RESULTS Data were collected from 129 and 92 patients on zidovudine (with lamivudine and nevirapine) and tenofovir (with emtricitabine and efavirenz) regimens, respectively. Compared to patients receiving the zidovudine regimen, patients receiving the tenofovir regimen had fewer adverse drug reactions (47%, 61/129 vs 11%, 10/92; p<0.01), requiring fewer regimen changes (36%, 47/129 vs 3%, 3/92; p0.01). With the propensity score, the zidovudine regimen had 8 times more adverse drug reactions (p<0.01). Opportunistic infections were similar between regimens without propensity score, while the zidovudine regimen had 1.2 times (p=0.63) more opportunistic infections with propensity score. Patients on the tenofovir regimen gained more weight. Increase in CD4 levels and treatment adherence (>95%) was similar across regimens. CONCLUSIONS Patients on a tenofovir regimen have better clinical outcomes and improved general health than patients on the zidovudine regimen.