Table 1.

Validity of Different Register-Based Definitions of Inflammatory Bowel Disease. N (%) if Not Otherwise Stated

Register-Based Definitions	Proportion True IBD	PPV (95% CI)
2 or more diagnostic listings of IBD in the NPRa	216/233	93% (89–96)
IBD diagnosis according to SWIBREGb	58/58	100% (94–100)
1 or more diagnostic listings of IBD in the NPR and a pathology code suggestive of IBDc	202/212	95% (91–98)
2 or more diagnostic listings of IBD in the NPR and a pathology code suggestive of IBDc	202/208	97% (94–99)

Notes: ^aProportion of patients who fulfilled the Copenhagen criteria for an IBD diagnosis (n=209), OR who did not fulfil the above criteria but were very likely to have IBD according to the medical chart review (n=7) among individuals with at least two diagnostic listings of IBD in the NPR (n=233). ^bProportion of patients who fulfilled the Copenhagen criteria among patients with at least two diagnostic listings of IBD in the NPR and an IBD diagnosis according to SWIBREG (Swedish Quality Register for inflammatory bowel disease). ^cPathology codes suggestive of IBD are listed in Supplemental Table S1A.

Abbreviations: NPR, National Patient Register; IBD, Inflammatory Bowel Disease.