A Population-based Study of Incidence, Risk Factors, Clinical Spectrum, and Outcomes of Ischemic Colitis

Background and Aims: Little is known about progression of ischemic colitis (IC) among unselected patients. We aimed to estimate the incidence, risk factors, and natural history of IC in a population-based cohort in Olmsted County, Minnesota. Methods: We performed a retrospective population-based cohort and nested case-control study of IC. Each IC case was matched to 2 controls from the same population on the basis of sex, age, and closest registration number. Conditional logistic regression, the Kaplan-Meier method, and proportional hazards regression were used to assess comorbidities, estimate survival, and identify characteristics associated with survival, respectively. Results: Four hundred forty-five county residents (median age, 71.6 years; 67% female) were diagnosed with IC from 1976 through 2009 and were matched with 890 controls. The age-adjusted and sex-adjusted incidence rates of IC nearly quadrupled from 6.1 cases/100,000 person-years in 1976-1980 to 22.9/100,000 in 2005-2009. The odds for IC were significantly higher among subjects with atherosclerotic diseases; odds ratios ranged from 2.6 for individuals with coronary disease to 7.9 for individuals with peripheral vascular disease. Of IC cases, 59% survived for 5 years (95% confidence interval, 54%-64%), compared with 90% of controls (95% confidence interval, 88%-92%). Age>40 years, male sex, right-sided colon involvement, concomitant small bowel involvement, and chronic obstructive pulmonary disease were all independently associated with mortality (P < .05). Conclusions: The incidence of IC increased during the past 3 decades in a population-based cohort in Minnesota. IC typically presents in older patients with multiple comorbidities and is associated with high in-hospital mortality (11.5%) and rates of surgery (17%).