Changes and predictors for change to thiazolidinedione prescribing in UK primary care following the rosiglitazone safety warning.

OBJECTIVE

To investigate switching from thiazolidinediones, and predictors for switching treatment, after publication of a meta-analysis reporting an increased risk of myocardial infarction associated with rosiglitazone use.

RESEARCH DESIGN AND METHODS

Using the Health Information Network (THIN) UK primary care database, the number of people with type 2 diabetes prescribed either thiazolidinedione, rosiglitazone (n = 10,062) or pioglitazone (n = 4454), and the rate of switching from thiazolidinediones (n = 3301 and 1106, respectively), were computed for each month, May 2006 to January 2008. The probability of switching post-publication, May 2007 to January 2008, was modelled by logistic regression in a forward stepwise model. Variables included demographics, history of ischaemic heart disease (IHD), heart failure (HF) or stroke, risk factors for IHD, glucose-lowering and cardiovascular drug use, HbA(1c) and diabetes duration.

RESULTS

There was a sharp increase in switching from both thiazolidinediones in summer 2007; rosiglitazone prescription numbers then decreased while pioglitazone prescribing increased. Switching from rosiglitazone was associated with IHD [adjusted odds ratio (OR) 1.72; 95% confidence intervals (CI) 1.47-2.00], insulin treatment (OR 5.10; 95% CI 3.21-8.10), HF (OR 2.26; 95% CI 1.62-3.18), a recent sulphonylurea prescription (OR 1.33; 95% CI 1.17-1.51) gender (OR men vs. women 0.79; 95% CI 0.70, 0.90) and duration of therapy. Switching from pioglitazone was associated with HF (OR 3.05; 95% CI 1.77-5.26), duration of therapy, and number of glucose-lowering treatments.

CONCLUSIONS

Prescribing habits for both thiazolidinediones changed immediately following the safety warning. IHD was associated with switching from rosiglitazone; otherwise reasons for change appear to be complex, not directly related to the findings of the meta-analysis.