Bisphosphonate use: Asian American women have a smaller treatment benefit

A large observational study showed that the reduction of clinical fractures by bisphosphonates outweighs the risk of bisphosphonate-associated atypical femur fractures. However, Asian Americans have a higher risk for these fractures, thus diminishing their advantage of therapy, in particular in the long term.

Concerning patient safety, Prof. Jinoos Yazdany (University of California San Francisco, USA) selected a study on bisphosphonates in her lecture ‘Year in review’ as particularly relevant for daily practice [1]. Although bisphosphonates are effective in reducing osteoporotic fractures, concerns about atypical femur fractures (AFFs) have contributed to substantially decreased bisphosphonate use. To further explore these uncertainties, a large observational study was performed including 196,129 women ≥50 years of age that received bisphosphonates [2]. All patients were members of the Kaiser Permanente Southern California healthcare system and were followed for a period of >10 years. The primary outcome was AFFs. Data on risk factors, including bisphosphonate use, was obtained from electronic health records. “What I liked about this study is that they radiographically adjudicated AFFs, which is a methodologic improvement over previous studies,” Prof. Yazdany said. There were large numbers of Asian American and Latinx patients in the whole population.

In total, 277 AFFs occurred. Indeed, the use of bisphosphonate increased the risk of AFFs. The incidence of fractures increased with a longer duration of bisphosphonate intake with a substantial increase in risk about the 5-year mark, a time point where many colleagues consider a drug holiday. “The most interesting finding of this study was that the risk for AFFs was much higher in Asian American women compared with other ethnic groups,” said Prof. Yazdani. Asian American women had a 4.84-fold elevated risk (95% CI 3.57–6.56) compared with White women. Bisphosphonate discontinuation was associated with a rapid decrease in the risk of AFFs. Decreases in the risk of osteoporotic and hip fractures during 1–10 years of bisphosphonate use far outweighed the increased risk of AFFs in White women. However, the benefit was less pronounced among Asian American women, especially after 10 years. “After 10 years the number of prevented hip fractures (360) and AFFs (236) almost converge, so I believe we have to think about drug holidays for this patient group,” Prof. Yazdani concluded.

Figure. The number of clinical fractures prevented by bisphosphonates outweighs the risk of biphosphonate-associated AFF in all ethnicities. However, Asian Americans have a considerably smaller treatment benefit. Adapted from [2]



AFFs, atypical femur fractures.

 

1. Yazdany J, Atypical Femur Fractures risk with bisphosphonates. 1T001, ACR Convergence 2020, 5-9 Nov.
2. Black MD, et al. New Engl J Med 2020;383:743-53.

Posted on 18 January 202117 May 2024