A randomized, pilot trial to evaluate glomerular filtration rate by creatinine or cystatin C in naïve HIV-infected patients after tenofovir/emtricitabine in combination with atazanavir/ritonavir or efavirenz.

BACKGROUND: Glomerular filtration rate (GFR) estimated by Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation based on creatinine or cystatine C may be more accurate methods especially in patients without chronic kidney disease. There is lack of data on GFR estimated by these methods in patients on HAART.METHODS: Antiretroviral-naïve HIV-infected patients were randomized to TDF/emtricitabine (FTC) in association with ATV/r or EFV. Patients had to have an actual creatinine clearance >50 ml/min (24 hour urine collection) and were followed for 48 weeks.RESULTS: Ninety-one patients (48 ATV/r, 43 EFV) were recruited. Using the CKD-EPI creatinine formula, there was a significant decrease in GFR up to week 48 in patients receiving ATV/r (4.9 mL/min/m; P =0.02) compared to a not statistically significant increment in patients prescribed EFV. Using the cystatin C-based equation, we found greater decrease in GFR in both arms, although, in the EFV arm, the decrease was not statistically significant (5.8 mL/min/m, P=0.92). At multivariable analysis, ATV/r was a significant predictor of greater decrease in eGFR (P=0.0046) only with CKD-EPI creatinine.CONCLUSIONS: ATV/r plus TDF caused greater GFR decreases compared to EFV. The evaluation of eGFR by cystatin C confirmed this result but this method appeared to be more stringent, probably precluding the possibility to detect a significant difference in the pattern of eGFR evolution between the two arms over time. More studies are needed to understand the clinical relevance of these alterations and whether cystatin C is a more appropriate method for monitoring GFR in clinical practice.