Various factors could cause higher risk in Asian women
The reasons for the increased risk among Asian women are likely multifactorial and could include greater medication adherence among Asian women, genetic differences in drug metabolism and bone turnover, and, notably, increased lateral stress caused by bowed Asian femora, the authors speculated.
Further questions include whether the risk is limited to Asians living outside of Asia and whether cultural differences in diet or physical activity are risk factors, they added.
“At this early stage, further research into the cause of the increased risk among women of Asian ancestry is warranted,” they wrote.
Although the risk for AFF may be higher among Asian women, the incidence of hip and other osteoporotic fractures is lower among Asians as well as other non-White persons, compared with White persons, they added.
The findings have important implications in how clinicians should discuss treatment options with different patient groups, Dr. Cheung said.
“I think this is one of the key findings of the study,” she added. “In this day and age of personalized medicine, we need to keep the individual patient in mind, and that includes their racial/ethnic background, genetic characteristics, sex, medical conditions and medications, etc. So it is important for physicians to pay attention to this. The risk-benefit ratio of these drugs for Asians will be quite different, compared to Caucasians.”
No link between traditional fracture risk factors and AFF, study shows
Interestingly, although older age, previous fractures, and lower bone mineral density are key risk factors for hip and other osteoporotic fractures in the general population, they do not significantly increase the risk for AFF with bisphosphonate use, the study also showed.
“In fact, the oldest women in our cohort, who are at highest risk for hip and other fractures, were at lowest risk for AFF,” the authors wrote.
The collective findings “add to the risk-benefit balance of bisphosphonate treatment in these populations and could directly affect decisions regarding treatment initiation and duration.”
Notable limitations of the study include the fact that most women were treated with one particular bisphosphonate, alendronate, and that other bisphosphonates were underrepresented, Dr. Cheung said.
“This study examined bisphosphonate therapy, but the vast majority of the women were exposed to alendronate, so whether women on risedronate or other bisphosphonates have similar risks is unclear,” she observed.
“In addition, because they can only capture bisphosphonate use using their database, any bisphosphonate exposure prior to joining Kaiser Permanente will not be captured. So the study may underestimate the total cumulative duration of bisphosphonate use,” she added.
The study received support from Kaiser Permanente and discretionary funds from the University of California, San Francisco. The study began with a pilot grant from Merck Sharp & Dohme, which had no role in the conduct of the study. Dr. Cheung has served as a consultant for Amgen. She chaired and led the 2019 International Society for Clinical Densitometry Position Development Conference on Detection of Atypical Femur Fractures and currently is on the Osteoporosis Canada Guidelines Committee.
A version of this article originally appeared on Medscape.com.