title: Smoking influences the need for surgery in patients with the inflammatory bowel diseases: a systematic review and meta-analysis incorporating disease duration.
abstract: BACKGROUND
  Studies examining the association between smoking and the need for surgery in patients with Crohn's disease and ulcerative colitis have reached inconsistent conclusions. These studies often do not differentiate between patients undergoing early surgery and patients having surgery later in their disease course. Our study examined the association between smoking status and time to first bowel resection in patients with Crohn's disease and ulcerative colitis.
  
  
  METHODS
  We searched MEDLINE and EMBASE for studies (n = 12) reporting on the association between smoking status (current, former, and never) and surgery in IBD, and incorporated disease duration in the analysis. Hazard ratios (HR) with 95% confidence intervals (CI) were pooled across studies using random effects models.
  
  
  RESULTS
  Current smokers with Crohn's disease were at increased risk of intestinal resection compared to never smokers (HR 1.27, 95% CI 1.08 to 1.49); however, there was no difference in the need for surgery when comparing former and never smokers (HR 1.11, 95% CI 0.95 to 1.30). In patients with ulcerative colitis, there was no difference in the need for colectomy when comparing current smokers to never smokers (HR 0.98, 95% CI 0.67 to 1.44). Former smokers with ulcerative colitis were at increased risk of colectomy (HR 1.38, 95% CI 1.04 to 1.83) compared to never smokers.
  
  
  CONCLUSIONS
  Current smokers with Crohn's disease are at increased risk of surgery, while former smokers with ulcerative colitis have increased risk of colectomy.
authors.affiliation: Department of Medicine, University of Calgary, 3280 Hospital Drive NW, 6D56, Calgary, AB, T2N 4N1, Canada.|Department of Community Health Sciences, University of Calgary, Calgary, AB, Canada.|Synder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada.|O'Brien Institute for Public Health, University of Calgary, Calgary, AB, Canada.
authors.forename: M Ellen
authors.initials: ME
authors.lastname: Kuenzig
authors.affiliation: Department of Medicine, University of Calgary, 3280 Hospital Drive NW, 6D56, Calgary, AB, T2N 4N1, Canada.|Department of Community Health Sciences, University of Calgary, Calgary, AB, Canada.|Synder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada.|O'Brien Institute for Public Health, University of Calgary, Calgary, AB, Canada.
authors.forename: Sang Min
authors.initials: SM
authors.lastname: Lee
authors.affiliation: Department of Medicine, University of Calgary, 3280 Hospital Drive NW, 6D56, Calgary, AB, T2N 4N1, Canada.|Synder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada.
authors.forename: Bertus
authors.initials: B
authors.lastname: Eksteen
authors.affiliation: Department of Medicine, University of Calgary, 3280 Hospital Drive NW, 6D56, Calgary, AB, T2N 4N1, Canada.|Department of Community Health Sciences, University of Calgary, Calgary, AB, Canada.
authors.forename: Cynthia H
authors.initials: CH
authors.lastname: Seow
authors.affiliation: Department of Medicine, University of Calgary, 3280 Hospital Drive NW, 6D56, Calgary, AB, T2N 4N1, Canada.|Department of Community Health Sciences, University of Calgary, Calgary, AB, Canada.
authors.forename: Cheryl
authors.initials: C
authors.lastname: Barnabe
authors.affiliation: Department of Medicine, University of Calgary, 3280 Hospital Drive NW, 6D56, Calgary, AB, T2N 4N1, Canada.
authors.forename: Remo
authors.initials: R
authors.lastname: Panaccione
authors.affiliation: Department of Medicine, University of Calgary, 3280 Hospital Drive NW, 6D56, Calgary, AB, T2N 4N1, Canada. ggkaplan@ucalgary.ca.|Department of Community Health Sciences, University of Calgary, Calgary, AB, Canada. ggkaplan@ucalgary.ca.|Synder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada. ggkaplan@ucalgary.ca.|O'Brien Institute for Public Health, University of Calgary, Calgary, AB, Canada. ggkaplan@ucalgary.ca.
authors.forename: Gilaad G
authors.initials: GG
authors.lastname: Kaplan
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D003082:Colectomy / Q000706:statistics & numerical data*; D003093:Colitis, Ulcerative / Q000473:pathology / Q000601:surgery*; D003424:Crohn Disease / Q000473:pathology / Q000601:surgery*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D064887:Observational Studies as Topic; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D013997:Time Factors; D055815:Young Adult
keywords: Cigarette smoking; Colectomy; Crohn’s disease; Inflammatory bowel disease; Intestinal resection; Meta-analysis; Survival analysis; Ulcerative colitis