The incidence and age of onset of inflammatory bowel disease (IBD) appear to be changing.
Dr Plevy and colleagues undertook a study in order to determine whether the prevalence of cigarette smoking differs among patients with Crohn's disease (CD) or ulcerative colitis (UC) at the time of diagnosis compared with the general population.
In addition, they aimed to determine whether smoking history is related to the type and age of IBD onset.
The researchers examined the prevalence rates of smoking at the time of IBD diagnosis between patients with crohn's and ulcerative colitis from the IBD Center at the University of Pittsburgh Medical Center.
The research team compared these rates to age-, gender-, and time period-adjusted rates in the Pennsylvania general population.
Analyses were also stratified by gender and diagnoses before and after 40 years of age, i.e., early and late onset.
|Smoking prevalence was significantly lower in UC patients than the general population (9% versus 28%)|
|Inflammatory Bowel Diseases|
The researchers noted that a total of 263 inflammatory bowel disease patients (144 UC patients and 119 CD patients) had been seen in the IBD center between August 2000 and December 2002.
The research team found that the prevalence of active smoking was significantly higher at diagnosis in crohn's disease patients compared with the Pennsylvania general population (33% versus 24%).
The team found that this was particularly noticeable in those with crohn's disease onset at 40 years of age or later (47% versus 27%).
In contrast, the researchers noted that smoking prevalence was significantly lower in ulcerative colitis patients than the general population (9% vs 28%), particularly among those with ulcerative colitis onset before the age of 40 years (6% vs 27%).
Smoking cessation was associated with an approximate, but nonsignificant, 3-fold higher likelihood of late-onset ulcerative colitis compared with crohn's disease.
Dr Plevy concluded, "Cigarette smoking is associated with the development of late-onset crohn's disease and is protective against developing ulcerative colitis at any age, particularly early onset."
"Former smoking is associated with a high likelihood of developing late-onset ulcerative colitis, but not crohn's disease."