OBJECTIVE: In Crohn's disease (CD), the relationship between genetic predis
position and smoking has not been well defined. The aim of this study was t
o compare the smoking habits at the time of the diagnosis of CD patients ha
ving familial occurrence of inflammatory bowel disease (IBD) with those of
some control groups.
METHODS: In a multicenter study, 136 CD patients with a relative with IBD,
272 healthy controls matched for sex and age, 500 CD patients without famil
ial occurrence of IBD, and 84 ulcerative colitis patients (UC) with familia
l occurrence of IBD were personally interviewed about their smoking habits.
In addition, data for 35 healthy siblings of patients with familial CD wer
e collected by interviewing the patients' relatives.
RESULTS: The prevalence of smokers was found significantly higher in CD pat
ients with a family history for IBD than in healthy controls and in familia
l UC patients (OR 2.28 CI 1.5-3.48 and OR 5.81 CI 3.15-10.75, respectively)
. No significant difference was found either in the percentage of smokers o
r in the number of cigarettes smoked per day between familial and sporadic
CD patients. Among all siblings of CD patients, 72% of affected siblings an
d 34% of healthy siblings were smokers, concordant with their relatives.
CONCLUSIONS: In CD patients with familial occurrence of IBD, the percentage
of smokers is elevated. It is possible that in a genetically predisposed p
opulation, smoking could be an important environmental factor in determinin
g CD or expressing this disease instead of UC, (C) 2000 by Am. Cell. of Gas
troenterology).