PrEP Does Not Appear to Cause Permanent Bone Loss
BETA is reporting from the 2016 Conference on Retroviruses and Opportunistic Infections (CROI) this week in Boston—bringing you the latest news, updates, and research on HIV treatment and prevention.
One of the drugs contained in PrEP drug Truvada, tenofovir disoproxil fumarate (TDF), has been associated with small decreases in bone mineral density. Researchers have raised concerns that PrEP use may prevent peak bone mass formation and increase risk of fractures. At CROI today, results were presented of a study demonstrating that bone mineral density returns to normal levels after people stopped taking PrEP. The implications of this study may be important for providers who counsel clients about the benefits and risks of starting and stopping PrEP.
“Recovery of BMD [bone mineral density] after stopping PrEP has not been fully evaluated,” said Robert M. Grant, MD, the lead investigator of the study of the Gladstone Institutes, the University of California San Francisco and San Francisco AIDS Foundation. “Bone mineral density appears to be a dynamic and regulated process that does return to placebo levels after stopping PrEP.”
The bone mineral density study was conducted with a subset of participants who participated in the oral PrEP iPrEx randomized controlled trial and open-label extension. A total of 498 men and transgender women received bone mineral density scans (DXA scans) of the spine and hip at the iPrEx baseline visit, every 24 weeks during the study, and when they enrolled in the open-label extension portion of the iPrEx trial. The median age of participants was 25 years and 11% identified as transgender.
Among people assigned to take active drug during the randomized controlled portion of the study, the average hip and spine bone mineral density decreased from the time study drug was begun. (Analyses were focused on people in the study who achieved drug levels corresponding to taking at least 2 to 3 tablets of study drug per week.)
“You can see that changes in bone mineral density occurred in both the hip and the spine. They occurred by week 24 and there was no substantial decrement after week 24,” said Grant.
After drug was stopped, and before participants enrolled into the open-label extension portion of the study, bone mineral density in both the hip and the spine increased. People under age 25 experienced a faster return to normal levels than people over age 25.
People under age 25 recovered bone mineral density of the hip and spine by six months after stopping drug. People older than 25 recovered bone mineral density completely in the spine within six months, and completely in the hip by the start of the open-label extension. (The median time between the randomized controlled study and the open-label extension was 1.5 years.)
It is not yet known how a second exposure to PrEP (as in, for example, the open-label extension portion of the iPrEx study) affects bone mineral density. Grant reported that participants in the iPrEx open-label extension did receive DXA scans every 24 weeks, and his team plans to present those results later this year.
Grant, R. and others. Abstract 48LB. Recovery of bone mineral density after stopping oral HIV preexposure prophylaxis. CROI 2016.