Absolute risk of atypical fracture with bisphosphonates is low, data suggest
Bisphosphonates are associated with a small absolute risk of atypical fracture, according to findings from a large, population-based study funded by the Swedish Research Council.
Researchers used the National Swedish Patient Register to establish that 12,777 women aged 55 and older had sustained a fracture of the femur in 2008. They reviewed X-rays for 1,234 women who had a subtrochanteric or shaft fracture and identified 59 patients who had atypical fractures. These were compared with 263 control patients who had ordinary shaft fractures.
The study, published in the New England Journal of Medicine (2011;364:1728), reported a high prevalence of current bisphosphonate use among patients with atypical fractures — 78 per cent compared with 10 per cent of the controls.
The age-adjusted relative risk of atypical fracture was 47.3 (95 percent confidence interval, 25.6 to 87.3). However, the increase in absolute risk was just 5 cases per 10,000 patient years (95 percent confidence interval, 4–7), the authors of the study note.
The risk appeared to be unrelated to the use of systemic glucocorticoids and other drugs with effects on bone and was independent of coexisting conditions and age. The duration of bisphosphonate use influenced the risk but after drug withdrawal the risk diminished rapidly, falling by 70 per cent per year.
The authors say: “With a correct indication, the benefits of fracture prevention with bisphosphonate use will greatly outweigh the risk of atypical femoral fracture.”
Citation: The Pharmaceutical Journal URI: 11075083
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