incidence , defined as time of onset of symptoms of inflammatory bowel disease , rose from baseline rates in the 1930s to peak in 1980 ( crohn 's disease = 50.29/10 ( 5 ) per decade , ulcerative colitis = 35.12/10 ( 5 ) per decade ) and declined through 1986 .
C0021390
inflammatory bowel disease
C0010346
crohn 's disease