Benefits of bisphosphonates outweigh atypical femur fracture risk in women
Click Here to Manage Email Alerts
The reduced risks for osteoporotic and hip fractures with bisphosphonate therapy outweigh increased risk for atypical femur fractures for older women, according to study finding published in Bone.
“Concerns about atypical femur fracture among patients have led to decreased acceptance of bisphosphonates,” Dennis M. Black, PhD, professor and division head of clinical trials and multicenter studies in the department of epidemiology and biostatistics at the University of California, San Francisco, and colleagues wrote. “However, growing body of data from large, well-conducted observational studies shows that for the great majority of patients, the benefits of reduction in hip, clinical and spine fractures far outweigh the risks of atypical femur fractures. Our growing understanding of clinical risk factors for atypical femur fractures will soon allow us to target therapies and their duration more precisely.”
Researchers analyzed data from 196,129 women aged 50 years or older who used bisphosphonates for at least 3 months in the Kaiser Permanente Southern California Osteoporosis Cohort Study (53.3% white, 24% Hispanic, 13.5% Asian, 5.9% Black). Demographics, medication usage and fracture history were obtained from electronic health records. Follow-up took place from 2007 to November 2017.
There were 277 atypical femur fractures reported in the study cohort. After multivariable adjustment, women aged 65 to 74 years (adjusted HR = 2.76; 95% CI, 1.62-4.72; P < .001) and aged 75 to 84 years (aHR = 2.5; 95% CI, 1.47-4.23; P = .001) had a higher risk for atypical femur fractures compared with those aged 85 years and older. Among racial ethnic groups, Asian women had a higher risk for atypical femur fractures compared with white women (aHR = 4.84; 95% CI, 3.57-6.56; P < .001).
Duration of bisphosphonate use was associated with an increase in atypical femur fracture risk, which gradually increased with 3 to 5 years of use (aHR = 8.86; 95% CI, 2.79-28.2; P < .001), 5 to 8 years of use (aHR = 19.88; 95% CI, 6.32-62.49; P < .001) and more than 8 years of use (aHR = 43.51; 95% CI, 13.7-138.15; P < .001). However, incidences of hip fractures were significantly higher than atypical femur fractures, with the difference increasing with older age group.
A higher rate of hip fracture incidences was observed in all racial-ethnic groups compared with atypical femur fracture incidence rates. The difference was less pronounced among Asian women, who had six atypical femur fractures per 10,000 person-years and 20.4 hip fractures per 10,000 person-years compared with 1.1 atypical femur fractures per 10,000 person-years and 81.2 hip fractures per 10,000 person-years in white women.
“While the relationship between bisphosphonate treatment and atypical femur fractures is present, the risk-benefit balance remains highly favorable for hip fracture and other clinical osteoporotic fractures versus atypical femur fractures,” the researchers wrote. “Atypical femur fractures are extremely rare, while hip, vertebral and other osteoporotic fractures are much more common and can be successfully prevented through treatment.”
Researchers observed a reduced risk for atypical femur fractures for women who had not used bisphosphonates within the previous 1.25 years (aHR = 0.52; 95% CI, 0.37-0.72; P < .001), between 1.25 and 4 years (aHR = 0.21; 95% CI, 0.13-0.34; P < .001) and for more than 4 years (aHR = 0.26; 95% CI, 0.14-0.48; P < .001).
“The dramatic decrease in risk of atypical femur fractures after discontinuing bisphosphonates, coupled with the retention of benefits for fracture reductions for the first few years after discontinuation supports the value of drug holidays,” the researchers wrote.
Collapse
Click Here to Manage Email Alerts