Concordance of familial characteristics in Crohn's disease and ulcerative colitis.

The diagnosis of inflammatory bowel disease (IBD) in a proband increases the probability of a parallel IBD diagnosis in a family member. In this study, we were able to confirm the IBD diagnosis in 35 (9.9 percent) of the relatives of 352 registry probands. To confirm a proband's report of a positive family history of IBD, efforts were made to directly contact all first-degree relatives regardless of their IBD status (parents, siblings, and children). Consent to contact family members was obtained from the proband, who furnished the registry personnel with names, addresses, and phone numbers. We then attempted to contact each identified relative by phone. After verbal consent was obtained, family members were asked if they had been diagnosed with IBD. This diagnosis was confirmed by contacting the relative's physician. A McNemar (chi 2 Mc) matched-pair analysis was used to analyze concordance between the proband and the affected family member. Within the CD/CD (Crohn's disease) concordant pairs, sex was a significant risk factor. Sex was not a significant risk factor within the UC/UC (ulcerative colitis) concordant pairs. In the concordant surgery pairs, no surgical procedure was a significant risk factor for the prediction of a similar surgical procedure for the affected relative. In concordant extraintestinal complications, only the appearance of a skin rash was significantly related to the appearance of a skin rash in the affected relative.