Survival and cause specific mortality in patients with inflammatory bowel disease: a long term outcome study in Olmsted County, Minnesota, 1940-2004

Abstract

Background and aims: We followed a population based cohort of patients with inflammatory bowel disease (IBD) from Olmsted County, Minnesota, in order to analyse long term survival and cause specific mortality.

Material and methods: A total of 692 patients were followed for a median of 14 years. Standardised mortality ratios (SMRs, observed/expected deaths) were calculated for specific causes of death. Cox proportional hazards regression was used to determine if clinical variables were independently associated with mortality.

Results: Fifty six of 314 Crohn's disease patients died compared with 46.0 expected (SMR 1.2 (95% confidence interval (CI) 0.9-1.6)), and 62 of 378 ulcerative colitis (UC) patients died compared with 79.2 expected (SMR 0.8 (95% CI 0.6-1.0)). Eighteen patients with Crohn's disease (32%) died from disease related complications, and 12 patients (19%) died from causes related to UC. In Crohn's disease, an increased risk of dying from non-malignant gastrointestinal causes (SMR 6.4 (95% CI 3.2-11.5)), gastrointestinal malignancies (SMR 4.7 (95% CI 1.7-10.2)), and chronic obstructive pulmonary disease (COPD) (SMR 3.5 (95% CI 1.3-7.5)) was observed. In UC, cardiovascular death was reduced (SMR 0.6 (95% CI 0.4-0.9)). Increased age at diagnosis and male sex were associated with mortality in both subtypes. In UC but not Crohn's disease, a diagnosis after 1980 was associated with decreased mortality.

Conclusions: In this population based study of IBD patients from North America, overall survival was similar to that expected in the US White population. Crohn's disease patients were at increased risk of dying from gastrointestinal disease and COPD whereas UC patients had a decreased risk of cardiovascular death.