The use of three oral bisphosphonates nearly triples the risk of developing bone necrosis, a condition that can lead to disfigurement and incapacitating pain, say researchers in an article in the Jan. 15 online issue of The Journal of Rheumatology.
Researchers at University of British Columbia (UBC) and Vancouver Coastal Health Research Institute (VCHRI) conducted an epidemiologic study of bone necrosis and bisphosphonates taken by women to help prevent bone fractures due to osteoporosis. This study of 87,837 elderly patients was the first to explore the link between bone necrosis and the bisphosphonates alendronate, etidronate and risedronate.
The main outcome measure in the study was the risk ratio (RR) of aseptic osteonecrosis (AON) among ever-users of oral bisphosphonates (most recent drug exposure within 90 days of diagnosis) compared with that among past users (drug exposure between 91 and 365 days before diagnosis). As a quality measure, researchers also calculated RR for AON among patients who used statin and angiotensin-converting enzyme inhibitors (ACE-I) compared with patients who did not.
Researchers found that the adjusted RR for AON among bis-phosphonate users was 2.87. The adjusted RRs among bisphosphonate users who received alendronate, etidronate and risedronate were 2.87, 2.43 and 3.34, respectively. The adjusted RR for users of statins and ACE-I were 0.79 and 1.16, respectively.
They found no significant differences in RR for AON among current bisphosphonate users and past bisphosphonate users.
"Given the widespread use of these drugs, it is important that women and their doctors know the risks that come with taking them," said principal investigator Mahyar Etminan, PharmD, MSc, of the Centre for Clinical Epidemiology and Evaluation at UBC and VCHRI.
