People older than 40 experience greater average declines in kidney function while taking Truvada (tenofovir/emtricitabine) as pre-exposure prophylaxis (PrEP).
Publishing their findings in The Lancet HIV, researchers from the iPrEx open-label extension (OLE) presented a new analysis looking at adherence to daily Truvada and kidney function test results.
The analysis included 1,224 initially HIV-negative transgender women and cisgender men who have sex with men (MSM) between the ages of 18 and 70 in Brazil, Ecuador, Peru, South Africa, Thailand and the United States. They were all given open-label Truvada and instructed to take it daily. The study did not restrict entry based on kidney function.
The participants made study site visits every 12 weeks—7,475 visits all told—at which their creatinine clearance, an indication of kidney function, was tested. For a subset of 220 participants, researchers took hair samples—at a cumulative 1,114 visits—to test for adherence to the daily Truvada regimen.
During a median follow-up period of 72 weeks, participants experienced an average decline in creatinine clearance of 2.9 percent. Those who were 40 to 50 years old at the beginning of the study saw an average creatinine clearance decline of 4.2 percent while those who were older than 50 experienced an average decline of 4.9 percent.
After adjusting the data for various factors, the researchers found that being older and starting the study with a creatinine clearance of less than 90 milliliters per minute predicted declines in kidney function. They also found an association between adhering well to Truvada and a decline in kidney function.
The researchers concluded: “Our data suggest that the frequency of safety monitoring for PrEP might need to be different between age groups and that pharmacological measures can monitor for toxic effects as well as adherence.”
To read the study abstract, click here.