Appendectomy, smoking habits and the risk of developing ulcerative colitis : a case control study in private practice setting

Summary Objectives The strongest environmental factors identified for ulcerative colitis(UC) are cigarette smoking and appendectomy. However, most studies have been performed using case-controls from hospital-based populations. The purpose of this study was to compare the history of previous appendectomy and smoking habits in a group of patients with UC and a control group, followed by gastroenterologists in private practice. Methods We performed a case control studyin which 100 physicians recruited UC-patients and age and sex matched controls. Data were collected during a single visit. Based on a standardized questionnaire, UC patients and controls were divided into never, former or current smokers, and into subjects with or without a previous history of appendectomy. Results One hundred and ninety eight age- and sex-matched pairs of UC patients and controls were included. The prevalence of appendectomy in the UC-patients and control group was 12% and 46%, respectively. The pairwise-matched OR of ulcerative colitisfor previous appendectomy was 0.10 (95% CI, 0.05-0.21) (P versu s current smokers was 2.40 (95% CI 1.31-4.38) (P=0.004). In UC-patients, the OR of family history of UC compared with controls was 2.80 (95% CI, 1.01-7.77) (P=0.048). Conclusions This case-control studyconfirmed a strong negative correlation between both appendectomy and tobacco smoking, and ulcerative colitisin patients followed-up by gastroenterological practitioners.