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We were interested to hear the results of a number of trials of novel therapies for Crohn’s disease (CD) that were presented at the l2th UEGW and reported in abstract form in Gut.1–6 Many of the studies were randomised controlled trials in which the active and control groups were reported to have identical baseline characteristics. However, in all of the studies that were reported there was no mention of the smoking status of the participants, consistent with recent therapeutic trials in CD published in high profile journals.7,8 Smoking is a well documented and universally recognised risk factor for increased CD severity as smokers are more likely to relapse and require corticosteroids, immunosuppressants, and surgery.9,10 Furthermore, smokers are more likely to have a less favourable response to infliximab.11 Smoking status is therefore a potential confounding factor in therapeutic trials in Crohn’s disease. We urge investigators to include smoking status in the abstract, text, and analyses of all therapeutic trials of CD. Furthermore, we believe that stratification for smoking should be included at the planning stage for all randomised controlled trials in CD. Investigators may wish to re-analyse published data to ensure that results have not been confounded by smoking.
Conflict of interest: None declared.
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