OBJECTIVES: To compare all-cause resource utilization and health care costs between patients with diverticular disease (DD) and matched controls. METHODS: Medical and pharmacy claims data from the Ingenix IMPACT Managed Care database were analyzed (2005–2008, >40 health plans, all geographic regions within the US represented). Patients with DD were defined as those with primary diagnosis of colonic diverticulitis (≥1 claim) followed by acute antibiotic treatment within 3 days of diagnosis (n=36,636); first diverticulitis claim defined study index date. Controls from the same database were matched 2:1 based on age, gender, and plan enrollment dates (n=73,272); the index date was the date of their respective match from the DD group. Study eligibility required plan enrollment for ≥6 months pre-index and ≥12 months post-index. Outcomes were evaluated over 12 months post-index. Generalized linear models and negative binomial regression models were used to estimate resource utilization and health care costs. Costs were adjusted to 2009 dollars. RESULTS: Rates of resource utilization and health care costs were significantly higher for DD patients than for controls: hospitalization, ER visits, and office visits were 8-fold (Incidence Rate Ratio [IRR]=8.1), 4-fold (IRR=3.7), and 2-fold (IRR=2.3) higher, respectively, than in controls; all P<0.0001. Due to higher resource utilization, adjusted mean total annual all-cause costs were substantially higher in DD patients than controls ($16,933 vs. $7,028; P<0.0001). The major drivers for the cost difference were hospitalizations ($6,554 vs. $1,374), ER visits ($1,022 vs. $120), outpatient/ancillary costs ($4,289 vs. $2,168), and office visits ($2,280 vs. $1,420); all P<0.0001. CONCLUSIONS: The economic burden of patients with DD is significant, with substantial costs occurring in cost sectors such as hospitalization, ER, and office visits. Interventions are needed to reduce diverticulitis occurrences and potentially decrease the costs associated with hospitalization, ER visits, and outpatient/ancillary services. Supported by funding from Shire Development Inc.