(Reuters) – Adults taking HIV pre-exposure prophylaxis (PrEP) have an overall low risk of renal impairment, but a new study suggests that risk is greater for people over age 50 and those with preexisting renal dysfunction.
Researchers examined data on 6,808 adults (99% male) in Australia who initiated PrEP between March 1, 2016, and April 30, 2018, and had renal assessments at baseline at least once more during a median follow-up period of 1.2 years. Participants took PrEP with disoproxil fumarate/emtricitabine (TDF/FTC).
During follow-up, the overall rate of new onset renal impairment was relatively low, at 5.8 episodes per 1,000 person-years. The threshold for new-onset renal impairment was an estimated glomerular filtration rate (eGFR) of less than 60 mL/min per 1.73 m2.
However, participants at least 50 years old (hazard ratio, 14.7) and individuals with baseline renal dysfunction (eGFR less than 90 mL/min per 1.72 m2) (HR, 28.9) were significantly more likely to develop renal impairment during the study period than younger people and those without baseline renal dysfunction.
“To clinicians, we would say that risk of renal impairment in young patients with normal renal function is incredibly low,” said lead study author Douglas Drak of the University of Sydney.
“For those with risk factors, the absolute risk remains low, and they should still offer TDF-containing PrEP to patients at risk of HIV infection,” Mr. Drak said by email. “More frequent monitoring in these patients should be considered though, as prompt discontinuation of TDF-containing PrEP has been shown to largely reverse the associated renal impairment.”
The median age of patients in the study was 35 years, and 14% were 50 years or older. At baseline, 27% of participants had renal dysfunction.
It’s possible that renal impairment was more common in the current study than in previous research because the current study had a higher proportion of patients who were over 50 or had baseline renal dysfunction, the study teamin AIDS.
The main limitation of the study is the relatively brief follow-up period, which may not have been sufficient to determine rates of renal impairment with longer periods of PrEP exposure, researchers note.
“Renal function declines with age normally, so risk is always higher with older age, and the finding of no renal adverse events among people younger than 40 is consistent with prior reports and is reassuring,” said Dr. Robert Grant, a professor of medicine at the University of California, San Francisco, who wasn’t involved in the study.
While PrEP with FTC/TDF is safe, alternative PrEP drugs should be used when patients have renal insufficiency before they start PrEP, Dr. Grant said by email.
If renal tests show an issue during PrEP, the first step is to confirm the result using a second blood specimen, Dr. Grant advised. Most abnormalities will not be confirmed, and likely reflect temporary dehydration not related to PrEP or random lab measurement variation, Dr. Grant said.
“If the abnormality is confirmed, people should stop PrEP with FTC/TDF and wait until the renal function normalizes,” Dr. Grant said. “Once that happens, they can restart PrEP, and they may also choose to switch to an alternative PrEP medication.”
Reuters Health Information © 2021