An evidence-based approach to studies of the natural history of gastrointestinal diseases: Recurrence of symptomatic Crohn's disease after surgery☆☆☆★

Patients with chronic disorders frequently ask about the prognosis of their disease. In some cases, this prognostic information may also guide management decisions. For example, a patient with Crohn's pancolitis may be willing to undergo colectomy if prognosis studies demonstrate that Crohn's disease is unlikely to return after surgery. However, if Crohn's disease is likely to return in the small intestine shortly after surgery, the patient may be less willing to agree to surgery. Before these questions about prognosis can be answered, appropriately designed studies must be completed and systematically appraised. This article, the third in the evidence-based medicine (EBM) series, provides an EBM framework to critically assess the design and results of a study about prognosis. This article examines the prognosis after colectomy for Crohn's colitis and follows the format of other EBM articles about prognosis. The EBM concepts have been expanded from previous articles, and examples from the gastroenterology literature have been used.

Abbreviations:  CI , confidence interval, EBM , evidence-based medicine