Switching from TDF to TAF or dual therapy (DT)-based regimens in HIV-infected in individuals with viral load <=50 copies/ml: does eGFR matter?

Our aim was to evaluate the association between most recent eGFR values and the risk of switching from TDF to TAF or to dual therapy (DT) separately for the two strategies in a reallife setting. HIV-positive patients, achieving HIV-RNA≤50 copies/ml for the first time after starting a TDF-based regimen (baseline) were included. Kaplan-Meier (KM) curves and Cox regression models were used to estimate the time from TDF to switch to TAF or DT. A total of 1,486 participants were included: median (IQR) age 36y(30-42), baseline CKD-EPI eGFR 99.92 (86.47,111.4) mL/min/1.73m2. We observed a consistently higher proportion of people with a HIV-RNA≤50copies/mL who have switched from TDF to TAF rather than to DT. By competing risk analysis, the 2 years from baseline, the probability of switching was 3.5% (95% CI 2.6- 4.7) to DT and 46.7% (95% CI 42.8-48.5) to TAF. A significant higher probability of switching to TAF was found for patients receiving INSTI at baseline versus NNRTIs and PI/b (KM: 65.6%, 95%CI 61.7, 69.4; vs. 4.0%, 95%CI 1.8, 6.1 and 59.9%, 95%CI 52.7, 67.2, respectively; p<.0001). A eGFR<60 ml/min/1.73m2 both as time-fixed covariate at baseline or as current value, was associated with a higher risk of switching to DT [aHR 6.68, 95%CI 2.69, 16.60 and 8.18, 95% CI 3.54, 18.90; p-value <0.001] but not to TAF-based cART [aHR= 0.94, 95%CI 0.39, 2.31, p=0.897 and 1.19, 95%CI 0.60, 2.38, p=0.617)]. In conclusion, counter to our original hypothesis, current eGFR value is used by clinician to guide switches to DT but does not seems to be a key determinant for switching to TAF. This should be taken into account when managing people on TAF-based regimens.