Renal Function in Antiretroviral-Experienced Patients treated with Tenofovir Disoproxil Fumarate associated with Atazanavir/ritonavir

Objective To determine the evolution of renal function in highly treatment-experienced patients with normal renal function at baseline receiving tenofovir disoproxil fumarate (TDF) as part of a fixed combined antiretroviral regimen and to identify prognostic factors of change in renal function, including tenofovir concentrations.Methods A prospective 48-week open-label trial was carried out, evaluating the safety of TDF, associated with atazanavir/ritonavir, and optimized nucleoside reverse transcriptase inhibitors, in patients with documented failure in previous treatments. Statistical analysis was performed on an intent-to-treat basis.Results Fifty-three patients were included, with a median CD4+T-cell count of 206x106/l and a median HIV RNA level of 5 log10copies/ml. All patients had normal serum creatinine levels and creatinine clearances (CLCr) at baseline, which were stable within the 2 months preceding inclusion. Two patients discontinued TDF as a result of severe renal impairment. Two patients never started TDF. A total of 49 patients without clinical nephrotoxicity were analysed. The median creatinine level increased significantly from baseline to week 48 (+0.04 mg/dl [+5.8%]; P=0.008), and the median CLCrdecreased significantly (-7.8 ml/min [-7.6%]; P=0.005). Trough tenofovir concentration was not associated with change in CLCr(P=0.79). No risk factors, including tenofovir plasma trough levels, were significantly associated with change in CLCrat week 24.Conclusions This study confirms that TDF-related severe nephrotoxicity is an uncommon event. In patients without clinical nephrotoxicity, the use of TDF during a 1-year period was associated with a slight but significant alteration of renal function, which was not associated with increased trough concentration.