OBJECTIVES: Previous studies demonstrate that diverticulitis (DV) is costly to payers. Most research focuses on total costs and acute episodes, while the burden of recurrent episodes is not well documented. This study assessed the direct economic burden associated with DV recurrence among managed care enrollees. METHODS: Data were drawn from insurance claims from ≥40 US health plans. Patients with a primary DV diagnosis (ICD-9-CM 562.11 or 562.13) between January 1, 2005 to December 31, 2008 were subjected to the following criteria: antibiotic treatment ≤3 days post-diagnosis and ≥6 months continuous pre- and ≥12 months post-index date (first observed DV diagnosis) plan enrollment. The first 6 weeks post-index date defined the initial acute episode period. Within a given 6-week period following the acute episode, a recurrent episode was defined by a DV-related hospitalization or ER visit, or a DV-related office visit with antibiotic treatment within ±3 days of the visit. Those with a recurrence were stratified into those with and without surgical intervention. Recurrence-related costs (2009 US$) were evaluated for 12 months post-initial acute episode. RESULTS: A totall 36,636 patients were selected (53% male, mean age 52 years); 16.5% (N=6,045) had ≥1 recurrence. Among those with ≥1 recurrence, the mean number (SD) of recurrences was 1.3 (0.6), while the total cost of all recurrences was ~4 times the initial acute episode cost ($12,806 vs. $3,132). For the surgical group (N=2868), the difference between the total cost of all recurrences and initial acute episode cost was still ~4 times ($24,247 vs. $6,903). For the non-surgical group (N=3177), however, the total cost of all recurrences was slightly less than initial acute episode costs ($2478 vs. $2648). CONCLUSIONS: Costs associated with recurrent DV episodes are significant, with recurrences costing substantially more than initial acute episodes. Among those with a recurrence, significant variation in costs among those with and without surgical intervention exists.