Switching from tenofovir containing regimens to boosted protease inhibitor monotherapy: Impact on renal function

Objective: To evaluate the effect on creatinine clearance (CG-CrCl, Cockcroft-Gault equation) of switching to boosted protease inhibitor (PI) monotherapy in patients receiving a triple drug antiretroviral regimen containing TDF.

Methods: All patients who had received a TDF-containing regimen for at least one year and had been switched to PI monotherapy were included. A rapid decrease in CG-CrCl during exposure to TDF was defined as a decrease in CG-CrCl at least five times higher than the expected due to age (0.4ml/min/year by the years of exposure to TDF). In this subgroup of patients, we considered improvement if the last value of CG-CrCl on PI monotherapy was 10% higher than the last value of CG-CrCl before switching to PI monotherapy. A multivariate logistic regression was constructed to identify factors associated to renal improvement after switching to bPI monotherapy.

Results: 64 patients included. The median (IQR) annual change in CG-CrCl during PI monotherapy was significantly lower than the median (IQR) annual change while exposed to TDF [-0.9 (-4.7 to +2.8) ml/min vs. -4 (-8 to -1) ml/min, p=0.001]. 44 patients experienced a rapid decline during TDF exposition. After switch to PI monotherapy, 15/44 (34%, 95% CI: 21-50%) had an improved CG-CrCl and 16/44 (36%, CI 23-52%) experienced a further decline in CG-CrCl. The only variable associated to CG-CrCl improvement was a more rapid CG-CrCl decline in the last year of exposure to TDF.

Conclusion: Switching to PI monotherapy partially reversed CG-CrCl decrease associated to TDF use, especially in patients with a more rapid decline while receiving TDF.