The clinical presentation of Crohn's disease varies from mild disease to frequent, severe exacerbations that require resection. In some patients, symptoms recur even after surgery. Only 12 percent of patients are relapse-free 10 years after diagnosis. Patients who require surgical resection most commonly have medical intractability, internal fistulas, intestinal obstruction, hemorrhage, toxic dilatation or acute perforation. A number of risk factors for postoperative recurrence have been implicated, including age, gender, disease location, preoperative duration of history and presence of granulomas. However, only smoking has been definitively associated with an increased risk of postoperative recurrence. Bernell and associates conducted a retrospective study to evaluate the probability of intestinal resection and the risk of recurrence in a population-based cohort.

Charts of patients with a confirmed diagnosis of Crohn's disease were reviewed, and the primary localization of disease was classified into one of six groups. Surgery was defined as any operation leading to intestinal resection. Postoperative recurrence was defined as the first day a patient presented with bowel symptoms consistent with Crohn's disease in which the condition was subsequently verified objectively by a diagnostic procedure, was actively treated, or both.

Of 1,936 patients diagnosed with Crohn's disease between 1955 and 1989, 1,424 (73.6 percent) required at least one intestinal resection. Disease localization had the greatest impact on the probability for surgery. Patients whose disease was localized to the small bowel or ileocecal area had the highest relative risk (3.2) for surgery. Those with orojejunal or continuous ileocolonic disease had a relative risk of 1.8. Patients with perianal fistulas had a relative probability of surgery of 1.2 compared with patients without fistulas. A patient age between 45 and 59 years at diagnosis was associated with a higher probability of surgery. A total of 682 (48 percent) surgical patients experienced a relapse. Women had a significantly higher relapse rate compared with men. Other factors associated with a higher relapse rate included disease localized to the small bowel and presence of perianal fistulas. Age and pre-operative disease duration did not appear to affect the risk of recurrence.

The authors conclude that three of four patients with Crohn's disease ultimately require intestinal resection, and one half of these patients experience a relapse. Crohn's disease involving any part of the small intestine and the presence of perianal fistulas increase the risk of postoperative relapse. Patients with ileocecal or colorectal disease appear to have a more favorable disease course. A relapse-free period of 10 years following the first resection implies remission maintenance.