Objectives: This study was conducted to determine the number of pioglitazone users before and after the issue of the pioglitazone safety warning (intervention) by South Korea's Ministry of Food and Drug Safety on June 10, 2011.
Study design: A quasi-experimental interrupted time series study was conducted to examine the number of pioglitazone and other antidiabetic drug users between 2009 and 2015.
Methods: We used the National Health Insurance Service-National Sample Cohort database to estimate the number of pioglitazone and other antidiabetic drug users between 2009 and 2015. Relative and absolute changes in the number of drug users were calculated with 95% CIs. Monthly numbers of drug users were presented according to the maximum likelihood estimation method, and a segmented regression analysis was performed to evaluate the effect of the intervention. A Durbin-Watson statistic and Dickey-Fuller test were used to assess autocorrelation and seasonality, respectively.
Results: A total of 80,724 patients with diabetes, including 12,249 pioglitazone users, were investigated. The relative change in pioglitazone users was -8.13% (95% CI, -8.41% to -7.86%). The intervention was associated with an immediate decrease of 177 pioglitazone users per 1000 patients with diabetes (P <.05). Without this intervention, the predicted proportion of pioglitazone users would be 90 per 1000 patients with diabetes, which is 1.5-fold higher than the actually observed rate of 60 per 1000 patients with diabetes.
Conclusions: This intervention led to a moderate decrease in pioglitazone users. Until further evidence is available, caution should be exercised when prescribing pioglitazone to patients with high potential risk of bladder cancer and alternative treatments should be considered.