Smoking is a risk factor for incisional hernia.

HYPOTHESIS A number of risk factors for incisional hernia have been identified, but the pathogenesis remains unclear. Based on previous findings of smoking as a risk factor for wound complications and recurrence of groin hernia, we studied whether smoking is associated with incisional hernia. DESIGN Cohort study. Clinical follow-up study for incisional hernia 33 to 57 months following laparotomy for gastrointestinal disease. Variables predictive for incisional hernia were assessed by multiple regression analysis. SETTING Department of Surgery, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark. PATIENTS All 916 patients undergoing laparotomy from 1997 through 1998. Surgeons performed clinical examination in 310 patients; patients who failed to meet for examination, died, or were lost to follow-up were excluded. MAIN OUTCOME MEASURES Thirty-four variables related to patient history, preoperative clinical condition, operative severity and findings, and the surgeon's training. RESULTS The incidence of incisional hernia was 26% (81/310). Smokers had a 4-fold higher risk of incisional hernia (odds ratio [OR], 3.93 [95% confidence interval (CI), 1.82-8.49]) independent of other risk factors and confounders. Relaparotomy was the strongest factor associated with hernia (OR, 5.89 [95% CI, 1.78-19.48]). Other risk factors were postoperative wound complications (OR, 3.91 [95% CI, 1.99-7.66]), age (OR, 1.04 [95% CI, 1.02-1.06]), and male sex (OR, 2.17 [95% CI, 1.21-3.91]). CONCLUSION Smoking is a significant risk factor for incisional hernia in line with relaparotomy, postoperative wound complications, older age, and male sex.