Kidney function not improved in patients who switch to TAF-based PrEP

Patients who switch from tenofovir disoproxil fumarate (TDF) to tenofovir alafenamide fumarate (TAF) for HIV pre-exposure prophylaxis (PrEP) do not experience improved kidney functioning, according to study results published in Open Forum Infectious Diseases.

The use of TAF-based HIV PrEP is hypothesized to have better safety profile for kidney toxicity compared with the use of TDF-based PrEP. However, it is not known whether kidney function can be improved among patients who switch from TDF- to TAF-based PrEP regimens.

Researchers conducted a retrospective cohort study using data sourced from Kaiser Permanente Southern California. Adult patients (N=528) with HIV infection who initiated TDF-based PrEP between 2014 and 2021 were included in the analysis. Patients who switched to TAF between October 2019 and May 2022 were matched 1:4 against those who continued TDF via time-varying propensity score matching. The primary outcome was kidney function for up to 18 months post-switch, which was assessed via estimated glomerular filtration rate (eGFR).

The researchers used the recorded switch date for patients who switched to TAF and an assigned switch date for those who continued TDF as the index date for the follow-up period. Bayesian linear mixed-effects models were used to evaluate eGFRs among patients in the TAF group in a counterfactual scenario in which the switch had never occurred. The model was adjusted for patient sex, age at TDF initiation, race and ethnicity, insurance type, smoking status, cardiometabolic comorbidities, and body weight.

Among patients who switched to TAF (n=118) and those who continued TDF (n=410), the mean (SD) age was 44.86 (12.80) and 38.00 (10.62) years, 99.2% and 97.3% were men, 50.0% and 43.9% were White, and the mean body (SD) weight was 84.19 (17.09) and 85.41 (19.49) kg, respectively.

At baseline, patients in the TAF cohort had significantly lower mean (SD) eGFRs (86 [21] mL/min/1.73m²) than those in the TDF cohort (100 [16] mL/min/1.73m²).

Between 3 and15 months post-switch, a statistically nonsignificant increase in eGFR was observed among patients in the TAF cohort when compared with those in the TDF cohort. The largest between-group difference in eGFR (mL/min/1.73 m²) was observed at month 12 (mean difference, 2.26; 95% credible interval, -1.35 to 3.89), with a reversal of this difference observed at month 18 (mean difference, -1.90; 95% credible interval: -6.82 to 2.94).

There was no clinically meaningful difference in eGFR observed between the groups, and similar trends were observed in weighted and inverse propensity matching analyses.

Limitations of this study include the retrospective design, missing data, the short follow-up period, and the use of eGFR measurements to assess kidney function rather than clinical events.

“Our results do not support that switching from TDF to TAF would improve eGFR in our sample of insured patients using PrEP,” the researchers noted. “Confirmatory studies with larger cohorts and longer follow-up or randomized switch or crossover trials are needed to confirm our findings,” they concluded.

Disclosures: Multiple study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

By Jessica Nye, PhD

References:

Rivera AS, Pak K, Mefford MT, Hechter RC. Changes in glomerular filtration rate after switching from tenofovir disoproxil fumarate to tenofovir alafenamide fumarate for HIV pre-exposure prophylaxis. Open Forum Infect Dis. Published online December 29, 2023. doi:10.1093/ofid/ofad695