Glomerular filtration rates in HIV-infected patients treated with and without tenofovir: a prospective, observational study

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Abstract
The aim of our study was to assess the impact of plasma HIV-1 RNA level [viral load (VL)] variation and tenofovir exposure on kidney functions by analysing changes in calculated glomerular filtration rates (GFRs) over a 48 week period in patients with mild renal impairment. A prospective observational study that included data from all consecutive HIV-infected patients who attended a metabolic clinic was conducted. Included were adult, antiretroviral (ARV)-experienced, tenofovir-naive patients, whose kidney functions were evaluated by calculated GFR using the simplified Modification of Diet in Renal Disease study equation (MDRD). Tenofovir-exposed patients were patients who initiated tenofovir therapy at baseline and tenofovir-unexposed patients were patients whose ARV therapy did not include tenofovir. Participants were stratified into three sub-groups according to the plasma HIV-1 RNA (VL) changes observed: sub-groups 1, 2 and 3 were patients with stable VL ≤50 copies/mL, >0.5 log10 VL increases and >0.5 VL log10 decreases, respectively. Ninety-nine patients were enrolled and included in the analysis. Within the tenofovir-unexposed group, GFRs remained stable (ANOVA, P = 0.94) over the follow-up period. Within the tenofovir-exposed group, mean GFR changes varied significantly by sub-group (ANOVA, P < 0.01). In particular, GFR changes in sub-group 3 (+8.4 ± 12.4 mL/min) were different from those seen in sub-group 1 (−1.0 ± 8.8 mL/min) (P < 0.05) and sub-group 2 (−4.6 ± 8.8 mL/min) (P < 0.01). Observed improvements in GFR that occurred as a consequence of highly active ARV therapy-induced viral suppression may have more than offset any potential negative effects of tenofovir on renal function.