Smoking, use of oral contraceptives, and medical induction of remission were risk factors for relapse in Crohn's disease

Question What are the risk factors for Crohn's disease in remission? Design 48 week study of patients in the placebo group of a randomised contr olled trial. Setting 31 clinical centres in Canada. Patients 152 patients (median age 34 y, 58% women) who were 18-82 years of age; had Crohn's disease with greater than or equal to 2 exacerbations in t he previous 4 years and 1 exacerbation or surgical resection in the previou s 18 months; were in remission (Crohn's Disease Activity Index less than or equal to 150); and had not received treatment with corticosteroids for gre ater than or equal to 30 days, immunosuppressants for less than or equal to 90 days, and mesalazine or metronidazole for 7 days before study entry. Ex clusion criteria were a history of proctocolectomy or malignant disease, sh ort bowel syndrome, >3 bowel resections in the previous 10 years, chronic p erianal disease, drug abuse, or major illness. Assessment of risk factors Smoking, use of oral contraceptives, disease loc ation and duration, age at diagnosis, time in remission, recent resection, history of blood transfusions, baseline disease activity, and quality of li fe were assessed in personal interviews. Main outcome measure Relapse. Main results 61 patients relapsed, 60 patients remained in remission, and 3 1 patients were withdrawn without relapse. Relapses occurred more frequentl y in women than in men (46% v 33%, p = 0.05) and in patients who achieved r emission after medical treatment than after surgery (46% v 25%, p = 0.02). Relapse was also associated with smoking status (current smokers 53%, forme r smokers 35%, non-smokers 30%; p = 0.02) and oral contraceptive use (curre nt use 43%, previous use 70%, no use 27%; p < 0.001). Multivariate analysis showed that an increased risk of relapse was associated with current smoki ng, previous or current oral contraceptive use, and medical induction of re mission; sex and previous smoking were not associated with an increased ris k of relapse (table). No interaction between smoking and oral contraceptive use occurred. Conclusion Current smoking, previous or current oral contraceptive use, and medical induction of remission were independent risk factors for relapse i n patients with Crohn's disease in remission.