In Reply Svendsen et al and Li et al suggest that the methods used in our Original Investigation1 misallocate person-time and may be biased by residual immortal time. This is due to a misinterpretation of our defintion of a warfarin user.
The definition of a warfarin-user in our study is: (1) a person who has at least 6 months between first and last prescription of warfarin, and (2) the first warfarin prescription is at least 2 years before any cancer diagnosis (2-year lag).1 The study period was January 1, 2006, to December 31, 2012, with information regarding warfarin prescriptions available starting January 1, 2004.