Table 1.

Sensitivity analysis using different criteria to determine prevalence of IBD, ulcerative colitis and Crohn’s disease.

Diagnosis	Prevalence definition*	Minimum enrollment	Prevalence per 100,000 population
IBD overall	Primary	4 year	721 (717–726)
IBD overall	Secondary	4 year	826 (821–831)
IBD overall	Primary	1 year	600 (597–603)
IBD overall	Secondary	1 year	680 (677–683)
Crohn’s disease	Primary	4 year	305 (302–308)
Crohn’s disease	Secondary	4 year	347 (344–350)
Crohn’s disease	Primary	1 year	258 (256–260)
Crohn’s disease	Secondary	1 year	290 (288–292)
Ulcerative colitis	Primary	4 year	378 (375–382)
Ulcerative colitis	Secondary	4 year	438 (435–441)
Ulcerative colitis	Primary	1 year	312 (310–314)
Ulcerative colitis	Secondary	1 year	358 (356–361)

^*Secondary definition includes patients with a single diagnosis of IBD by a gastroenterologist or surgeon, or two or more diagnoses by providers other than gastroenterologists or surgeons, without any therapy, applying a weight of 0.22