In a study published Online First by JAMA’s Archives of Internal Medicine, Raphael P. H. Meier, M.D., and his team from Geneva’s University Hospitals and Faculty of Medicine in Switzerland declare: “Current evidence suggests that there is an association between bisphosphonate therapy and atypical femoral fractures, but the extent of this risk remains unclear.”

The researchers analyzed 477 patients’ data, aged 50 years and older, who were hospitalized with a subtrochanteric or femoral shaft fracture at a single university medical center together with a random sample of 200 healthy individuals without any fractures.

The types of fractures sustained amongst the patients were identified as 39 patients with an atypical fracture, of which 32 patients or 82.1% were treated with bisphosphonates, whilst of the remaining 438 patients with a classic fracture, 28 patients or 6.4% received bisphosphonates. In comparison with those without fractures, bisphosphonates was linked to reduction risk of 47% in those that had sustained a classic fracture.

After categorizing the patients depending on the lengths of their treatment, as compared with no treatment, the treatment time for an atypical fracture compared with a classic fracture was 35.1 for a treatment period of less than 2 years, 46.9 for treatment durations of between 2 to 5 years and 117.1 for treatment periods ranging between 5 to 9 years and 175.7 for periods lasting longer than 9 years.

In a final statement the researchers write:

“In conclusion, we have demonstrated that the association between bisphosphonate treatment and the occurrence of atypical fractures of the femur is highly likely and that the duration of such treatment significantly correlates with augmented risk. However, the incidence rate was very low, and the absolute benefit to risk ratio of bisphosphonate use remains positive.”

Douglas C. Bauer, M.D., of San Francisco’s University of California states in an invited comment:

“The case control study by Meier et al in this issue of the Archives adds further data suggesting that the association between bisphosphonate use and atypical femur fractures is causal,” concluding that, “atypical femur fractures are uncommon but do appear to be more frequent among individuals who are being treated with oral and intravenous bisphosphonates, and longer duration of use further increases the risk. Additional studies of atypical fractures are needed to clarify the mechanism and other key risk factors as well as to confirm that discontinuation of treatment after long-term use substantially lowers the risk.”

Written By Petra Rattue