Letter: deleterious effects of smoking on post-operative Crohn's disease - authors’ reply

We thank Yamamoto et al. for taking the time to read our paper,1 and for their comments.2 We agree that it would have been useful to study the effect of tobacco smoking on the clinical course of Crohn's disease according to the amount smoked, duration of smoking behaviour, gender and disease location. Unfortunately, an insufficient number of the eligible studies, according to the inclusion criteria we used, reported these data in sufficient...