Thiazolidinedione use and the risk of fractures

The recent commentary by Lorraine Lipscombe1 gave the impression that the 10-study meta-analysis by Loke and colleagues yields a new finding that there might be an association between thiazolidinediones and an increased risk of fractures in women.2 In fact, this finding largely replicates an association reported 2 years ago in the publication of the results of ADOPT (A Diabetes Outcome and Progression Trial).3

GlaxoSmithKline reported the ADOPT findings to regulatory agencies worldwide; in Canada, the company also issued communications to both health care professionals4 and the Canadian public5 regarding this information. Working with Health Canada, GlaxoSmithKline has updated the product monograph for Avandia (rosiglitazone maleate) to include these data.

Lipscombe stated that clinical drug trials are often underpowered to detect unanticipated and rare adverse events and suggested that a standardized post-marketing surveillance process is needed.1 Rosiglitazone is the most studied oral agent for the treatment of diabetes, with many years of clinical trial experience. As soon as the new safety information was available, it was promptly communicated to regulatory agencies, quickly published and directly communicated to physicians and patients. As such, we submit that the current system has worked well. Additionally, GlaxoSmithKline is making significant efforts to investigate the effects of rosiglitazone on bone, including adding bone-specific analyses to several clinical studies to better understand these observations about fracture risk. Avandia remains a valuable tool in the treatment of type 2 diabetes; its role has been recognized and clarified in the 2008 revision of the Canadian clinical practice guidelines for diabetes.6