In the Journals

IBD risk higher in families already affected by IBD

The risk for developing inflammatory bowel disease is significantly higher among first-, second- and third-degree relatives of patients with inflammatory bowel disease, particularly in younger family members, according to recent study data.

“Estimates of familial risk of IBDs — Crohn’s disease and ulcerative colitis — are needed for counseling of patients and could be used to target future prevention,” Frederik T. Moller, MD, from Statens Serum Institut in Denmark, told Healio Gastroenterology.

Frederik T. Moller

To provide comprehensive population-based estimates of familial IBD risk, Moller and colleagues used national registry data to perform a cohort study of the entire Danish population from 1977 to 2011 (n = 8,295,773; mean follow-up, 24 years; 200 million person-years). They identified 45,857 IBD cases and data on first-degree (siblings, offspring, parents), second-degree (grandchildren, uncles, aunts and half-siblings) and third-degree relatives (half uncles and aunts, nephews, nieces and cousins).

Overall, 6.6% of CD cases and 4.8% of UC cases had a positive family history, although proportions for the most recent cohort (2007-2011) reached 12.2% and 8.8%, respectively. Among patients with CD with a positive family history, 72% had a first-degree relative with IBD, 23% had a second-degree relative with IBD and 5% had a third-degree relative with IBD, and the corresponding proportions for patients with UC were 77%, 19% and 4%, respectively.

The incidence rate ratios (IRRs) of CD and UC were significantly increased in relatives to someone with the same IBD:

  • CD; first-degree relative (IRR = 7.77; 95% CI, 7.05-8.56);
  • second-degree relative (IRR = 2.44; 95% CI, 2.01-2.96); and
  • third-degree relative (IRR = 1.88; 95% CI, 1.3-2.71).
  • UC; first-degree relative (IRR = 4.08; 95% CI, 3.81-4.38);
  • second-degree relative (IRR = 1.85; 95% CI, 1.6-2.13); and
  • third-degree relative (IRR = 1.51; 95% CI, 1.07-2.12).

Individuals who had more than one relative with IBD had a particularly high risk, and age-specific analysis showed that younger age groups also had a particularly high risk.

“In general, first-degree relatives of IBD cases had a seven-to-eight times increased risk of contracting IBD, compared with sporadic cases, and this risk was most pronounced in early life,” Moller said. “While the rate ratios presented may be more generalizable, the presented absolute risk estimates are applicable mainly in a setting with prevalence and incidence data compatible with Danish incidence and prevalence.” – by Adam Leitenberger

Disclosure: Moller reports no relevant financial disclosures. Please see the study for a full list of all other researchers’ relevant financial disclosures.

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