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Australian Study of BMD Changes for Men on PrEP
Who Are Adherent to Daily TDF/FTC PrEP
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Substantial Loss of Bone Mineral Density in Some Patients Receiving Tenofovir-Emtricitabine as HIV Pre-exposure Prophylaxis - Aim of Study
-to evaluate changes in BMD over 12 months in men adherent to daily TDF-FTC PrEP
Reported by Jules Levin
18th International Workshop on Comorbidities and Adverse Drug Reactions in HIV, September 12-13, 2016, New York
John McAllister, Dianne Morris, Sarah Holliday, Andrew Carr
HIV, Immunology and Infectious Diseases Unit
St Vincent's Hospital, Sydney, Australia
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More Than 5% BMD Loss With 1 Year of TDF/FTC PrEP in Half of Australian Group
18th International Workshop on Comorbidities and Adverse Drug Reactions in HIV, September 12-13, 2016, New York
Mark Mascolini
Half of an all-male Australian group using daily tenofovir/emtricitabine (TDF/FTC) preexposure prophylaxis (PrEP) had more than a 5% loss in bone mineral density (BMD) at one or more bone sites through 12 months of follow-up [1]. Four in five cohort members had more than 3% BMD loss at one or more sites. The findings contrast with results of prior PrEP studies in men who have sex with men (MSM), which found about a 1% drop in BMD during the first months of TDF/FTC [2,3].
Andrew Carr and colleagues at Sydney's St. Vincent's Hospital, who presented the new findings [1], noted that bone loss through 1 year of PrEP has proved reversible in previous studies. But whether bone loss during longer PrEP can be corrected remains unknown. Carr also observed that nonadherence in randomized controlled trials of PrEP is common, so some previously reported BMD loss rates may be underestimates. The St. Vincent's team aimed to measure changes in BMD over 12 months in men adhering to daily TDF/FTC PrEP by comparing DXA scans of L1 to L4 of the spine, left and right total hips, and left and right femoral necks at month 0 and month 12. They used the same scanner for all participants.
The analysis involved 34 men who began daily TDF/FTC PrEP in the PRELUDE PrEP demonstration project (NCT02206555). The group averaged 38.4 years in age and 79.9 kg in weight. They had taken TDF-containing postexposure prophylaxis (PEP) for an average 6.4 months. All men with month-12 DXAs filled all TDF/FTC PrEP prescriptions on time, but participant tenofovir levels were not available at the time of this presentation.
Through 12 months of PrEP, BMD dropped an average 2.2% in the lumbar spine (P = 0.004), 2.1% in the left plus right hips (P = 0001), and 2.5% at the left plus right femoral necks (P < 0.001). Proportions of men with more than 3% BMD loss at those sites were 44%, 34%, and 46%. Proportions with more than 5% BMD loss at those sites were 27%, 16%, and 25%. A large majority of men, 82%, had more than 3% BMD loss at the spine or one or both hips, and 53% had more than 5% loss at the spine or one or both hips. One third of men, 32%, had more than 3% BMD loss at the spine and one or both hips.
Carr and colleagues noted several potential limitations of their study: There was no control group; some of the measured BMD loss may reflect aging; they had no data on secondary causes of low BMD (though no one had diabetes, chronic liver disease, or chronic kidney disease); and follow-up lasted only 12 months.
The investigators proposed that identifying people with the highest risk of BMD loss during PrEP would "assist targeted screening and intervention." They suggested comparing BMD loss with daily TDF/FTC PrEP, before-and-after sex TDF/FTC PrEP, and non-TDF PrEP regimens. Carr stressed that more than 3% bone less at the spine or hips was the norm in this population, affecting 82%.
Based on research reported through 2014, the Centers for Disease Control and Prevention (CDC) did not recommend DXA scans before or during PrEP [4]. The CDC did suggest that "any person being considered for PrEP who has a history of pathologic or fragility bone fractures or who has significant risk factors for osteoporosis should be referred for appropriate consultation and management" [4]. Carr proposed that before-PrEP DXA scans may be prudent for people expecting to take TDF for a prolonged period, just as checking estimated glomerular filtration rate before starting TDF has become routine.
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