Previous studies suggest that smoking is an important environmental factor in inflammatory bowel diseases (IBDs), with dichotomous effects in ulcerative colitis (UC) and Crohn's disease (CD). The aim of this study was to analyze the relationship between smoking and IBD risk in a population-based database from Veszprem Province, which included incident cases diagnosed between January 1, 1977, and December 31, 2008.
Data from 1420 incident patients were analyzed (UC: 914, age at diagnosis: 38.9 years; CD: 506, age at diagnosis: 31.5 years). Both inpatient and outpatient records were collected and comprehensively reviewed. Overall, smoking frequency in the adult general population was 36.1%.
Of patients with CD, 47.2% were current smokers at diagnosis. Smoking was more frequent in male patients (P = 0.002) and was associated with an increased risk of CD (odds ratio, 1.96; 95% confidence interval, 1.63–2.37; P < 0.001). In contrast, current smoking was protective against UC (odds ratio, 0.33; 95% confidence interval, 0.27–0.41). The effect of smoking was linked to gender (in CD, more deleterious in male patients) and age at diagnosis and was most prominent in young adults, with a difference already being seen in 18- to 19-year-olds. In CD, a change in disease behavior (P = 0.02), location from ileal or colonic to ileocolonic (P = 0.003), arthritis/arthropathy (P = 0.002), need for steroids (P = 0.06), or AZA (P = 0.038) was more common in current smokers. Smoking in UC was associated with more extensive disease (P = 0.01) and a tendency for decreased need for colectomy (P = 0.06).
Current smoking was associated with the risk of IBD. This effect was linked to gender and age at diagnosis and was most prominent in young adults. No association was observed in pediatric or elderly patients. The deleterious and protective effects of smoking on the course in CD and UC were partially confirmed.
Article first published online 8 February 2013
*1st Department of Medicine, Semmelweis University, Budapest, Hungary
†Department of Medicine, Csolnoky F. Province Hospital, Veszprem, Hungary
‡Department of Medicine, Grof Eszterhazy Hospital, Papa, Hungary
§Department of Medicine, Municipal Hospital, Tapolca, Hungary
‖Department of Infectious Diseases, Magyar Imre Hospital, Ajka, Hungary
¶Department of Gastroenterology, Municipal Hospital, Varpalota, Hungary
**Department of Pediatrics, Csolnoky F. Province Hospital, Veszprem, Hungary.
Reprints: Peter L. Lakatos, MD, PhD, 1st Department of Medicine, Semmelweis University, Korányi S. 2/A, Budapest H-1083 Hungary (e-mail: firstname.lastname@example.org).
P. L. Lakatos and L. Lakatos received unrestricted research support from Schering-Plough Hungary/MSD. None of the funding bodies was involved in the study design, collection, analysis and interpretation of the data, or in the preparation of the manuscript.
P. L. Lakatos and Z. Vegh equally contributed to this study.
The authors have no conflicts of interest to disclose.
Received June 12, 2012
Accepted July 12, 2012