Among South-East Asian adults, bisphosphonate use in is not associated with differences in clinical outcomes or mortality after an atypical femur fracture, according to study data published in Bone.
“Asian patients are at higher risk of atypical femur fractures, with a possibility of highest risk in South-East Asian patients,” Linsey U. Gani, MPH, MBBS, consultant in the department of endocrinology at Changi General Hospital in Singapore, and colleagues wrote. “In this study, we set out to assess demographic and clinical characteristics of bisphosphonate- and non-bisphosphonate-related atypical femur fractures as well as their mortality in our population. To our knowledge, this is the first study in the South-East Asian population assessing differences in bisphosphonate- and non-bisphosphonate-related atypical femur fractures.”
Researchers conducted a cohort study of adults with acute fragility hip, subtrochanteric and femoral fractures who were admitted to Changi General Hospital from 2009 to 2015. The American Society for Bone and Mineral Research guideline from 2014 was used to classify fractures as atypical femur fractures. Baseline clinical data were collected from electronic health records. Medication data were obtained from Singapore’s national EHRs. Antiresorptive use was analyzed if the last medication was dispensed within 5 years of the fracture date and medication was dispensed for a duration of at least 6 months. Mortality data were collected until Dec. 31, 2019.
Researchers identified 69 atypical femur fractures, of which 35 were bisphosphonate related and 34 were not bisphosphonate related. There were no significant differences in demographics and clinical characteristics between those who sustained bisphosphonate-related fractures and those who had non-bisphosphonate-related fractures. The percentage of adults with a fragility fracture history was higher for those with bisphosphonate-related atypical femur fractures than those with non-bisphosphonate-related fractures (35.3% vs. 9.4%; P = .01).
Adults who had bisphosphonate-related atypical femur fractures took a longer time to heal compared with those with non-bisphosphonate-related fractures (3 months vs. 2 months; P = .02). There was no difference in bone mineral density values at the total hip and lumbar spine between the two groups. Mean survival times at 5 years were similar between the two groups, and the survival rate for both bisphosphonate-related and non-bisphosphonate-related atypical femur fractures was 85% at 5 years.
“Although atypical femur fracture is an unfortunate devastating event, it is reassuring that the mortality associated with both bisphosphonate- and non-bisphosphonate-related atypical femur fracture is low in comparison to the high mortality risk of typical subtrochanteric fractures in those with osteoporosis,” the researchers wrote. “In our analysis, we were not able to find major differences between bisphosphonate- and non-bisphosphonate-exposed atypical femur fractures, implying that these two groups are similar and should be classified as atypical femur fracture-prone patients.”
The researchers said future studies should focus on better understanding adults prone to atypical femur fractures by looking at the possible roles of genotyping, the characterization of femoral geometry risk and the management of their osteoporosis.