Authors: Sicilia B, Lopez Miguel C, Arribas F, Lopez Zaborras J, Sierra E, Gomollon F.

Institution: Digestive Disease Unit, Miguel Servet University Hospital, Zaragoza, Spain.

Background: The pathogenesis of inflammatory bowel disease probably involves an interaction between genetic and environmental factors: cigarette smoking, appendectomy and oral contraceptives have been the factors most frequently linked to its aetiology

Results: A total of 103 patients were diagnosed with Crohn's disease in Aragon from 1st February, 1992 to 31st January, 1995. Of these 62 patients (60.2%) with Crohn's disease were smokers, compared with 42 (40.8%) controls (p<0.001). Cigarette smoking is considered a risk factor for Crohn's disease with an odds ratio of 3.09 (95% confidence interval, 1.58-6.05). After multivariate analysis, the positive association is maintained. A dose-dependent relation could not be demonstrated. No statistical differences (p=0.50) were detected in the analysis of previous appendectomy. Use of oral contraceptive acts as a risk factor with a p=0.048; odds ratio 2, 8, 95% confidence interval: 1.009-7.774; but this association disappears in the multivariate analysis. Eight patients had a family history (3 first degree and 5 second degree relatives) versus none of the controls (p=0.002). Of the variables studied for childhood hygiene none appeared significant.

Conclusion: Smoking, family history, and oral contraceptive use, appear as risk factors for developing Crohn's disease in univariate analysis, but only smoking remains significant in all models of multivariate analysis.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=11838611&query_hl=12&itool=pubmed_docsum

Authors: Kane SV, Flicker M, Katz-Nelson F.

Institution: University of Chicago, Chicago IL 60637, USA. skane@medicine.bsd.uchicago.edu

GOALS: To study the association between tobacco exposure and postoperative clinical recurrence in Crohn's disease patients and quantify the time to clinical relapse following surgical resection.

Background: It is well accepted that cigarette smoking has a negative impact on postoperative course in Crohn's disease. However, the effect of smoking to hasten clinical recurrence has not been clearly delineated.

Conclusion: Smoking is associated with clinical recurrence of Crohn's disease, and the time to clinical recurrence in smokers is shorter. Strategies for smoking cessation are warranted.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15599207&query_hl=20&itool=pubmed_docsum

Authors: Silverstein MD, Lashner BA, Hanauer SB, Evans AA, Kirsner JB.

Institution: Department of Medicine, University of Chicago Medical Center, Illinois.

Summary: Crohn's disease is a chronic disease of unknown etiology. Previous reports have suggested that cigarette smoking may be associated with the development of Crohn's disease. To examine this association, we conducted a case-control study of patients referred to a single practice over a 7-month period. The cigarette-smoking habits of 115 patients with Crohn's disease were compared with the cigarette-smoking exposure of 109 patients with the irritable bowel syndrome.

Patients with Crohn's disease were more likely to smoke at the time of symptom onset than were irritable bowel syndrome controls (age and sex adjusted odds ratio 3.71, 95% confidence interval 1.93-7.13). After the diagnosis of Crohn's disease, patients were less likely to quit smoking (odds ratio 0.35, 95% confidence interval 0.18-0.69) than controls.

This study demonstrates an association and a temporal relationship between cigarette smoking and Crohn's disease. For the exposure to be considered an etiologic factor for disease, biologic plausibility and pathophysiologic mechanisms require elucidation.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&list_uids=2912028&dopt=Abstract

Authors: Cottone M, Rosselli M, Orlando A, Oliva L, Puleo A, Cappello M, Traina M, Tonelli F, Pagliaro L.

Institution: Clinica Medica R, Divisione di Medicina Ospedale V. Cervello, Universita di Palermo, Italy.

Background: Smoking may be a risk factor for surgical recurrence of Crohn's disease. However, other variables associated with recurrence could be confounding factors for smoking. The aim of this study was to evaluate the role of smoking as an independent predictor of clinical, surgical, and endoscopic recurrence.

Results: Independent predictors of clinical recurrence by the Cox proportional hazard model were smoking (hazard ratio, 1.46; 95% confidence interval [CI], 1.1-1.8), extraintestinal manifestations (hazard ratio, 1.61; 95% CI, 1.0-2.5), and extent of disease (hazard ratio, 1.57; 95% CI, 1.0-2.4). Smoking was the only significant predictor of surgical recurrence (hazard ratio, 2.0; 95% CI, 1.2-2.3). For endoscopic recurrence, logistic regression showed that smoking (odds ratio, 2.2; 95% CI, 1.2-3.8) and extent of disease (odds ratio, 2.6; 95% CI, 1.0-6.7) were predictive factors of recurrence.

Conclusions: Smoking is an independent risk factor for clinical, surgical, and endoscopic recurrence in Crohn's disease.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&list_uids=8119535&dopt=Abstract

Authors: Somerville KW, Logan RF, Edmond M, Langman MJ.

Summary: In a case-control study 82 patients with Crohn's disease and matched controls drawn from general practice lists were questioned about their smoking habits.

Patients with Crohn's disease were significantly more likely to be smokers than the controls, and the association was stronger for smoking habit before the onset of the disease than for current smoking habit, the relative risks for smokers compared with non-smokers being 4.8 and 3.5 respectively.

Taken in conjunction with earlier data showing an association between non-smoking and ulcerative colitis, these results suggest that smoking habit may be an important determinant of the type of inflammatory bowel disease that develops in predisposed subjects.

Study link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&list_uids=6435736&dopt=Abstract