In Reply Drs Singh and Suchard suggest that we deviated from the prespecified protocol submitted to the US Food and Drug Administration by adjusting for calendar year and that this could explain differences between our interim results1 and the results recently published. They may not have known that this protocol change was requested by the Food and Drug Administration.
Ferrara A, Lewis JD, Habel LA. Pioglitazone Use and Risk of Bladder Cancer—Reply. JAMA. 2015;314(23):2568-2569. doi:10.1001/jama.2015.13915