Amprenavir and didanosine are associated with declining kidney function among patients receiving tenofovir

Objective: To examine the effect of antiretroviral agents and clinical factors on the development of tenofovir-associated kidney dysfunction. Methods: Observational cohort study of HIV-infected patients receiving tenofovir in an HIV clinic population. Patients' kidney function prior to initiating and while receiving tenofovir was evaluated in relation to other antiretroviral medications and demographic and clinical characteristics. Decline in kidney function was assessed by the glornerular filtration rate (GFR) as estimated by the Cockcroft-Gault (CG) equation, which incorporates weight. Logistic regression analysis was used to examine factors associated with GFR of > 90, 60-90,30-60, and < 30 ml/min per 1.73 m(2) while on tenofovir. Secondary analyses used the simplified Modification of Diet in Renal Disease (MDRD) equation. Results: Among the 445 patients initiating tenofovir, 51 (11%) developed a decline in kidney function. In multivariate analysis, there was a significant association between decline in kidney function and concurrent use of amprenavir [odds ratio (OR) 3.6; P= 0.045] and didanosine (OR, 3.1; P = 0.006), age over 50 years (OR, 4.4; P= 0.03), and lower baseline weight (OR, 0.95/kg; P < 0.001). Patients identified with kidney dysfunction by the MDRD equation did not fully overlap with those identified by the CG equation. Conclusions: Didanosine and amprenavir use, increased age, and lower baseline weight were significantly associated with risk for kidney dysfunction among patients receiving tenofovir. GFR results using the MDRD equation were inconsistent with those using CG, which highlights the impact of including weight in the estimation of GFR among HIV-infected patients. (c) 2007 Lippincott Williams & Wilkins.