A large Danish cohort provides useful information on the mortality effects of having inflammatory bowel disease (IBD) and how this has changed over the last three decades (Clin Gastroenterol Hepatol 2013; 11: 43-48).
Using a national cohort of all individuals living in Denmark between 1982-2010 (on average 5.3 million), the authors studied 36,080 patients with ulcerative colitis (UC) and 15,361 with Crohn’s disease (CD) in comparison to data from 2,858,096 matched controls (50 controls from each IBD patient) from the general population. For UC, the median age was 45.2 years and for CD 36.3 years.
- With UC, the first year of diagnosis carried a higher risk of dying (HR 2.43) then rapidly declined to around HR 1.1 after 2 years. Overall, long-term mortality was increased 10% among UC patients. Mortality from UC decreased from 1982 to 2010 due to decreased mortalities from gastrointestinal disorders, including colorectal cancer.
- Mortality was higher among patients diagnosed at younger ages. Patients diagnosed with UC in childhood or adolescence had a 2.15-fold higher relative mortality than patients diagnosed with UC at 60-79 years.
- Cause-Specific Mortality: during the first year after UC diagnosis, the HR ratio was increased markedly for gastrointestinal disease (HR 13.3) and infection (HR 9.17). These areas were most prominent at 10+ years, but the HR ratios had decreased to 1.95 and 1.64 respectively at that time.
- For CD, mortality was markedly increased in the first year with HR 3.69 and declined to HR 1.53 during years 2-4; HR was 1.49 at 10+ years following diagnosis. Overall, long-term mortality was increased 50% among CD patients. Unlike UC, no improvement in mortality rate occurred during the study.
- Cause-Specific Mortality: during the first year after CD diagnosis, the HR ratio was increased markedly for gastrointestinal disease (HR 23.02) and infection (HR 10.19). These areas were most prominent at 10+ years, but the HR ratios had decreased to 3.67 and 2.70 respectively at that time. Infections were not increased in the most recent decade, indicating that thiopurines and biologics have not increased the overall risk of fatal infections.
- While the relative risk of cardiovascular disease was only slightly increased (HR 1.11 for both CD and UC), this is important given the overall frequency of cardiovascular disease in the population. Presumably, systemic inflammation contributes to the formation of atherosclerosis.
- Suicide was also increased, especially in the first year after diagnosis (HR 2.05 for UC and HR 1.37 for CD)
Strengths of study: since Denmark has free access to health care and all citizens have a unique 10-digit personal identification, this enables capture of virtually all patients with IBD. Previous studies have validated the database to be accurate and that the IBD diagnoses have been validated.
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