Schafer, JJ et al. Changes in Body Mass Index and Atherosclerotic Disease Risk Score After Switching From Tenofovir Disoproxil Fumarate to Tenofovir Alafenamide.
Open Forum Infectious Diseases, Volume 6, Issue 10, October 2019, ofz414, https://doi.org/10.1093/ofid/ofz414
There has been a significant trend over the past few years to change patients’ antiretroviral therapy (ART) from tenofovir disoproxil fumarate (TDF)-containing regimens to tenofovir alafenamide (TAF) mainly for reasons related to renal and bone safety. This retrospective observational study evaluated BMI and ASCVD risk score changes in virologically suppressed persons with HIV who switched from TDF to TAF but maintained the other component of their ART, which was an INSTI in 54%, NNRTI in 32%, and PI in 18%. This cohort include 110 adult patients with a mean age of 50 years of whom 73% were males. All patients were on TDF-containing ART for at least one year and had two consecutive HIV-RNA levels of <200 copies/mL before changing to TAF. Body weight, BMI, and cholesterol levels were obtained one year before and then one year after the switch to TAF. In addition, ASCVD risk scores were calculated one year before and one year after medication change. The authors found significant increases in weight, BMI, total cholesterol, LDL, and ASCVD risk scores following the switch from TDF to TAF. Substituting TAF for TDF was associated with a 0.45 kg/m2 increase in BMI. The median ASCVD score rose from 6.9% to 8.1% after switching. Using a regression model that adjusted for age, sex, race, years with HIV, and concomitant medications that can cause weight gain, there was 13% average increase in ASCVD risk scores. Almost 51% of this cohort met the current statin-eligible criteria of having a risk score of 7.5% or greater.
This is an observational study so it does not establish a causal relationship between TAF and changes in BMI or lipid levels. However, similar findings were seen in clinical trials with TAF and have been reported in the literature from other groups. This study did not have data on caloric intake or physical activity, which also may have played a role. The mechanisms for these changes remain to be determined. In the interim, I believe the goal for our patients is to maintain healthy lifestyles with an emphasis on diet and exercise with the use of statin therapy when clinically indicated. Our clinical practice recently incorporated a full time registered dietitian as part of our treatment team who meets with our patients and provides dietary counseling.