Outpatient treatment of acute diverticulitis: rates and predictors of failure

Many patients with acute diverticulitis can be managed as outpatients, but the success rate of this approach has not been thoroughly studied. We analyzed a large cohort of patients treated on an outpatient basis for an initial episode of acute diverticulitis to test our hypothesis that outpatient treatment of acute diverticulitis is highly effective.

We analyzed patients within the Kaiser Permanente Southern California system (from 2006 to 2007) who were diagnosed with an initial episode of diverticulitis during an emergency room visit and subsequently discharged home. Each patient underwent a computed tomography (CT) scan for diagnosis or for confirmation of a diagnosis, and each radiologic report was evaluated regarding the presence of free fluid, phlegmon, perforation, and abscess. Treatment failure was defined as a return to the emergency room or an admission for diverticulitis within 60 days of the initial evaluation.

Our study included 693 patients, of whom 54% were women, the average age was 58.5 years, and 6% failed treatment. In multivariate analysis, women (odds ratio, 3.08 [95% CI, 1.31-7.28]) and patients with free fluid on CT scan (odds ratio, 3.19 [95% CI, 1.45-7.05]) were at significantly higher risk for treatment failure. Age, white blood cell count, Charlson score, and duration of antibiotics were not significant predictive factors.

In a retrospective analysis, among a cohort of patients who were referred for outpatient treatment, we found that such treatment was effective for the vast majority (94%) of patients. Women and those with free fluid on CT scan appear to be at higher risk for treatment failure.