Tenofovir-induced nephrotoxicity: A retrospective cohort study.

BACKGROUND Tenofovir (TDF) has been associated with renal function deterioration, but local data regarding the incidence and risk factors for this adverse event were lacking. OBJECTIVES To determine the incidence of nephrotoxicity in HIV-infected patients on tenofovir-based regimens and to evaluate risk factors involved in tenofovir-associated renal function decline. METHODS This is a single-centre retrospective cohort study of 440 HIV-infected adults who were started on tenofovirbased antiretroviral regimens. Data were extracted from electronic medical and pharmacy records. RESULTS A decline in eGFR of 25% or more was seen in 67 patients (15.2%) with an estimated incidence rate of 12 per 100 person-years. Among all 440 subjects, 22 discontinued TDF-based therapy due to renal complication. From multivariate analysis, the odds of developing >25% decrease in eGFR with tenofovir-containing regimen was three times higher for patients with baseline moderate renal impairment (HR 3.19; 95% CI, 1.43-7.12; p=0.005) and 14 times higher for patients with baseline severe renal impairment (HR 14.2; 95% CI, 11.20-170.7; p=0.036) as compared to those without pre-existing renal insufficiency. Age above 50 years and CD4 cell count of less than 50 were significantly associated with >25% decrement in eGFR. CONCLUSION The incidence rate of tenofovir-related renal dysfunction was found to be 12 per 100 person-years. Preexisting renal impairment, age 50 and above, and CD4 cell count below 50 as were predictors for renal function decline. Given that the use of tenofovir is escalating in Malaysia, increased awareness about this adverse event is essential.