Rosiglitazone use and associated adverse event rates in Canada between 2004 and 2010

We examined the change in the use of rosiglitazone-containing products (RCPs) Canada-wide between 2004 and 2010 and whether the rates of adverse events in association with RCP therapy in Canadian patients changed in this period to better understand the real world use of RCP medications and as part of a regulatory commitment by GlaxoSmithKline to Health Canada to assess whether there was an impact of a risk communication on cardiac safety.

RCP utilization data were obtained from IMS Brogan's longitudinal de-identified patient database (known as LRx) that tracks prescription activity using store-based data collection from pharmacies in all Canadian provinces. Adverse events (AEs), serious adverse events (SAEs) and cardiac AEs associated with RCP use in Canadian patients between April 2004 and December 2010 were identified from GlaxoSmithKline's AE database and, using the LRx data, rates per 100,000 patients were estimated.

A total of 239,184 patients were identified as having received at least one RCP prescription between 2004 and 2010 from the LRx. After excluding those with inconsistent gender or age, only one RCP prescription at the pharmacy, a prescription from a pharmacy that had not consistently reported for the past six years or an unreasonably high number of prescriptions, 180,936 patients remained for the analysis. The number of reports identified from the AE database that occurred between April 2004 and December 2010 was 1,037. The average monthly rates of AEs, SAEs and cardiac AEs decreased by 57%, 43% and 4%, respectively, between the observed periods, April 2004-October 2007 and November 2007-December 2010.

The findings of this analysis demonstrate a significant decrease in RCP use in Canada following a meta-analysis publication suggesting harm, which has been maintained. It is not possible to disentangle whether the continuing decline can be attributed to the meta-analysis, the changes in prescribing guidelines, media attention or a combination of some or all of these factors.