Defining diverticular fistula through inpatient admissions: a population study.

Background: Diverticular fistula, a pathologic connection from the colon to the skin or another organ, is an uncommon sequela of diverticular disease. It is generally considered an indication for surgery. The current literature is limited in terms of defining the epidemiology of this disease process. This analysis defines the demographics of fistulous diverticular disease on a national level.

Methods: A retrospective review of the 2018 National Inpatient Sample (NIS) was conducted, using ICD-10 codes for diverticular disease, diverticular-associated fistulas, and associated surgeries. Demographic factors were compared between groups, and several sub-group analyses were performed.

Results: A total of 7,105,498 discharges were recorded: 119,115 (1.68%) with non-fistulizing diverticular disease and 3,843 (0.05%) with diverticular fistula. Patients with diverticular fistula were more likely to be younger (64.7 v 68.2 years, p < .0001) and female (57.3% v 55.4%, p = 0.028) than patients with non-fistulizing disease. They were also more likely to undergo surgery (64.9% v 25.7%, p < .0001), to be admitted electively (44.7% v 12.0%, p < .0001), and to have a longer length of stay (LOS) (mean 8.07 v 5.20 days, p < .0001). Diverticular fistula patients that underwent surgery were more likely to be male (44.8% v 39.0%, p = 0.003), to be admitted electively (65.3% v 6.7%, p < .0001), and to have longer LOS (mean 8.74 v 6.81 days, p < .0001) than those who received medical treatment alone.

Conclusion: Diverticular fistula is a rare diagnosis, accounting for 0.05% of total admissions and 3.12% of admissions for diverticular disease. However, this is more common than the previously reported rate of < 0.1% of diverticular disease admissions. While surgery is generally indicated for diverticular fistula, only 64.9% of patients underwent surgical treatment. Although this study is limited by its retrospective nature and use of administrative data, our findings elucidate the prevalence and patterns of inpatient admissions for diverticular fistula in the United States.