Risk factors for the development of fistulas in Crohn disease

The pathophysiology of fistula formation in Crohn's disease is as yet poorly known. We, therefore, studied in 111 patients with Crohn's disease factors which may be associated with the development of fistulas. Male patients, patients with exclusively involved colon or extended disease of the colon and ileum as well as patients treated with prednisone demonstrated an increased relative risk to develop fistulas. In patients with ileitis alone and after laparatomy in combination with resection of the bowel the relative risk was less than 1. Furthermore, in 71% of the patients fistulas developed during active disease. In 65% the patients had underweight at the time of fistula formation. We conclude, that the localization of the disease, a factor which can not be influenced, as well as active disease and malnutrition, both factors which can be influenced, may be involved in the formation of fistulas in Crohn's disease.