Glomerular filtration rate estimated by cystatin C formulas in HIV-1 patients treated with dolutegravir, rilpivirine or cobicistat

As dolutegravir (DTG), rilpivirine (RPV) and cobicistat affect creatinine, but not cystatin C, tubular transport or serum concentration, the aim of the study was to compare estimated glomerular filtration rates (eGFRs) calculated by means of a standard creatinine formula with those calculated by means of the cystatin C formula in patients receiving these drugs. This was a cross-sectional study of HIV-1 infected patients with eGFR <90 ml/min/1.73 m2 (CKD-EPI-creatinine formula) on-treatment with regimens including DTG, RVP or cobicistat; cystatin C was measured after the switch to these regimens. eGFR was calculated by means of the CKD-EPI formulas (CKD-EPI-creatinine: eGFRcrea; CKD-EPI-cystatin C: eGFRcyst). eGFRcyst was compared with the last eGFR assessed before (eGFRcrea pre) and after the switch (eGFRcrea post). The primary end-point of the study was the difference between eGFRcyst and eGFRcrea post. One hundred and twenty patients were included. eGFRcrea pre was 80 (70-92) ml/min/1.73 m2. eGFRcrea post was significantly lower than eGFRcyst (65 [59-75] vs. 80 [69-95] mL/ min/1.73m2; p<0.001); eGFRcyst did not differ from eGFRcrea pre (p=0.544). The difference between eGFRcyst and eGFRcrea post was not significantly different among regimen groups (p=0.056). In HIV-patients with reduced eGFR treated with DTG, RPV or cobicistat, measuring eGFR by means of the CKD-EPI cystatin C formula is probably more relevant.