Link shown between PrEP use and loss of bone density

It has been known for some time that use of Truvada, and generic versions of tenofovir disoproxil fumarate/emtricitabine (TDF/FTC), has been associated with the loss of bone density in people living with HIV. But there has been a lack of data on how the drug combination affects HIV-negative people using it for HIV prevention.

Data presented at CROI 2022, from a study in the United States, aimed to investigate just that question.

Research

Dr Joseph Chang of Kaiser Permanente Medical Centre in Los Angeles and his colleagues conducted a retrospective analysis to assess the relationship between TDF/FTC PrEP and loss of bone density.

The study involved 7,698 adults from California who used TDF/FTC as pre-exposure prophylaxis from 2012 to 2020. Almost all of the participants were men, the majority were aged 18 to 39. Around 40% of participants had “good” adherence, whilst 60% had adherence below 90%.

Results

After an average follow up period of 502 days, 217 (3%) of the 7,698 participants had developed osteoporosis or osteopenia - both conditions of bone weakening and loss. This figure was similar to what is seen in people living with HIV who use TDF/FTC for the treatment of HIV.

Participants with Hepatitis B, cardiovascular disease, chronic kidney disease, or hypertension were more likely than other participants to face bone density loss.

Following a multifactorial analysis, the researchers found that people with better adherence to their PrEP regimen were at a greater risk of bone density loss. More than 90% of the 217 participants with osteoporosis or osteopenia were in the “good adherence” (90% to 100%) group, whilst in the <90% adherence group this figure was only 9%.

It should be noted that no new cases of HIV infection were detected during the entire study period, even among participants with lower adherence to their PrEP.

Conclusions

Based on the results of the study and analysis, the team have concluded that people who start TDF/FTC for pre-exposure prophylaxis should discuss the risks associated with bone density loss with their doctor, and undergo routine screening.

It is also sensible to start suggesting people move to event-based PrEP, where tablets are taken before-and-after sexual contact, rather than daily PrEP to reduce the risk of long term effects.

A new variant of the drug combination, tenofovir alafenamide/emtricitabine (TAF/FTC - brand name ‘Descovy’), was launched a couple of years back. The new combination has a lesser impact on bone and kidney health, but is associated with increased lipids and weight gain. It is also much more expensive than Truvada or generic formulations.