Treatment outcomes of tenofovir versus zidovudine-based first-line antiretroviral therapy regimens at Zewditu Memorial Hospital: A retrospective cohort study

Tenofovir-based regimen is the preferred first line treatment in Ethiopia despite limited local data on its effectiveness and tolerability over zidovudine-based regimen. Therefore, this study compared the outcomes of tenofovir and zidovudine-based regimens focusing on toxicity driven regimen substitution and mortality. A retrospective cohort study was conducted in Zewditu Memorial Hospital. All ART naïve patients who started ART between August 31, 2010, and August 31, 2013, were included. Data were collected by reviewing of patient’s medical records. Kaplan-Meier test and Cox regression analysis were used to compare survival for toxicity driven substitution and mortality, and to identify the independent predictors respectively. A total of 223 patients were included in this study, among which 164 (73.5%) TDF and 59 (26.6%) AZT-based regimens. A total of 71 (31.8%) primary outcomes such as toxicity driven regimen substitution, mortality, and lost to follow-up were observed, 48(29.3%) among TDF and 23(39.0%) in AZT-based regimens. The risk of toxicity driven regimen substitution was more than five times higher in AZT than TDF group (AHR=5.07, p=0.013). The estimated cumulative mortality at 6, 12, 18 and 24 months was 6, 9, 9 and 9% in TDF group whereas it was 9, 13, 13, and 13% in AZT group. There was no statistically significant difference in mortality and regimen failure between TDF and AZT groups. TDF-based regimen has superior outcome and better survival for toxicity driven regimen change than AZT-based regimen. This study finding supports recommendation of TDF-based regimen as preferred first-line ART.