Medically reviewed by Onikepe Adegbola, MD, PhD
Since prevention of IBD is better than cure, this study aims at estimating the occurrence of inflammatory bowel disease (IBD) in families. Clustering of certain characteristics, behaviors, or disorders within a family is referred to as familial aggregation.
In Alimentary Pharmacology & Therapeutics, researchers examined the odds of first-degree relatives (FDR) having IBD (compared to controls) by age of diagnosis, family history, and subtype of IBD. Researchers examined the incidence of future IBD in relatives of incident IBD patients in a cohort study.
Research And Findings From Previous Studies
IBD usually takes the form of Crohn’s disease (CD) or ulcerative colitis (UC). The study of familial aggregation was important because both environmental factors and genetic factors play a role in the pathogenesis of IBD. Previously, researchers studied IBD clustering in a variety of ways, but most of them were based on small clinical cohorts. They didn’t even include a control group.
Moreover, all studies assess the risk of IBD in relatives of patients with IBD and the general population, using cohort designs. Since the assessment of familial cases of IBD has been restricted to a certain extent, none of these studies have specifically examined the genetic perspectives of IBD. Therefore, to provide precise estimates of the familial association with IBD, researchers conducted a national case-control study.
They analyzed the frequency of FDR with IBD among patients with IBD ( compared to controls), by the age of diagnosis, type of family history, and type of IBD subtype. Furthermore, they examined the risk of IBD in a cohort study and referenced individuals from the general population.
A cohort study follows groups of people over time. Researchers use cohort study data to study the influences of the environment and social factors on human health.
New Approach And Nationwide Study
The study was performed in Sweden using their NPR (National Patient Register). In the NPR, researchers found at least two diagnostic listings for inflammatory bowel disease. The Total Population Register allowed matching up to 10 control individuals from the general population based on age, sex, birth year, and county of residence. Controls and cases were then restricted to those with ≥1 FDRs. Swedish Multi-Generational Register identified parents, siblings, and offspring of cases and matched controls.
What Did They Find?
FDRs of IBD cases were around 2–14 times more likely to have IBD than FDRs of controls, whereas the HR for future IBD in FDRs of IBD cases was around 3. Because of these associations, the magnitude varies by type of IBD and by age. Hence, when planning future screening programs and preventive interventions in IBD, the age at diagnosis of IBD in the index patient and the age of the healthy FDR should be considered.
In any screening program or initiative aiming to prevent IBD among healthy FDRs of patients with IBD, it is important to take the age at diagnosis of IBD into account. The fact that IBD undergoes a preclinical phase and irreversible bowel damage may already have occurred at diagnosis support a prevention strategy.
The results of this large nationwide, population-based study are potentially useful for researchers and clinicians interested in familial IBD and can help tailor future screening interventions.
It is also comforting for patients to know that individuals with an FDR who developed IBD at an elderly age were seldom themselves affected by it. Moreover, the observed differences in familial aggregation between elderly-onset, adult-onset, and childhood-onset diseases contribute to our understanding of IBD pathogenesis.
This supports the notion that genetic predisposition has a lesser impact on the risk of developing elderly-onset IBD than that of childhood-onset disease.
Halfvarson, J. F., Ludvigsson, J. F., Bresso, F., Askling, J., Sachs, M. C., & Olén, O. (2022). Age determines the risk of familial inflammatory bowel disease-A nationwide study. Alimentary pharmacology & therapeutics, 10.1111/apt.16938. Advance online publication. https://doi.org/10.1111/apt.16938