Background: The detrimental impact of diverticulitis on quality of life and health care expenditures, particularly among those with recurrent episodes is substantial. Overweight and obesity, as assessed through body mass index (BMI), are established risk factors for diverticulitis, but it is unknown whether more precise measures of visceral adiposity are associated with incident diverticulitis and recurrence.

Methods: We included 7,657 patients (mean age, 52.5 ± 15.5 years; male, 47%) enrolled in the Mass General Brigham Biobank who underwent at least one abdominal computed tomography (CT) scan from 2004 to 2019 without a history of diverticulitis, inflammatory bowel disease, or cancer. Individuals were followed for incident diverticulitis as determined using ICD-9/10 codes from the electronic health records. Recurrent diverticulitis was defined with a primary or admitting diagnosis code for diverticulitis recorded >30 days after an initial episode. Visceral fat area (VFA) and subcutaneous fat area (SFA) were quantified at the third lumbar vertebral level, using a validated fully automated deep-learning pipeline applied to abdominal CT. We evaluated the associations of VFA, SFA, and the visceral-to-subcutaneous fat ratio (VSR) with incident and recurrent diverticulitis using multivariable-adjusted Cox proportional hazards models.

Results: We documented 431 cases of incident diverticulitis over a median follow-up of 9.9 years, encompassing 76,892 person-years of follow-up. VFA and VSR were associated with incident diverticulitis. Compared to individuals in the lowest quartile, multivariable-adjusted hazard ratios (HRs) were 2.97 (95% confidence interval [CI], 2.01-4.39; P trend <.0001) for those in the highest quartile of VFA and 3.97 (95% CI, 2.64-5.97; P trend <.0001) for those in the highest quartile of VSR. Such associations were not materially different with strata of BMI (<25 kg/m², 25-29.9 kg/m², ≥30 kg/m²). Among a subset of 370 patients who were diagnosed with an initial episode of incident diverticulitis documented with abdominal CT (mean age at the initial episode, 59.7 ± 12.6 years; male, 51%), we ascertained 187 subsequent recurrent diverticulitis cases and 90 cases requiring hospital admission over a median follow-up of 4.5 years. While VFA, SFA, or VSR were not associated with the risk of recurrence, there was a suggestive association between higher VSR and increased risk for recurrence requiring hospitalization (HR, 2.06; 95% CI, 0.97-4.38; P trend, .04).

Conclusion: Our findings support the role of visceral adiposity in the etiopathogenesis of diverticulitis, which provides insight into potential mechanisms and preventive strategies. Our data also suggest that patients with diverticulitis who undergo CT scans may be risk stratified for recurrence requiring hospital admission through easily obtained measures of visceral adiposity.

Figure 1. Restricted cubic spline plots for the association of visceral fat area (A) and visceral-to-subcutaneous fat ratio (B) with the risk of diverticulitis according to body mass index (BMI) strata

Christopher Bridge

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