Identification of Childhood-Onset Inflammatory Bowel Disease in Swedish Healthcare Registers: A Validation Study.

The Swedish National Patient Register (NPR) is often used in observational studies of childhood-onset inflammatory bowel disease (IBD) (<18 years of age) and its subtypes, but the validity of previously used register-based algorithms for capturing childhood-onset IBD has never been examined. We identified a random sample of 233 individuals with at least two first ever diagnostic listings of IBD in the NPR between 2002 and 2014. We calculated the test characteristics for different register-based definitions of IBD and its subtypes using the Copenhagen criteria and the revised Porto criteria as gold standard, both based on medical chart review. We made assumptions of the occurrence of undiagnosed IBD in the general child population based on available literature. Out of 233 individuals with at least two diagnostic listings of IBD, 216 had true IBD, resulting in a positive predictive value (PPV) = 93% (95% confidence interval (CI) 89-96), sensitivity = 88% (95% CI 83-92), specificity = 100% (95% CI 100-100), and negative predictive value (NPV) = 100% (95% CI 100-100). The PPV for the NPR-based definitions of IBD subtypes at time of first IBD diagnosis and at end of follow-up were 78% (95% CI 69-86) and 88% (95% CI 80-94), respectively, for Crohn's disease and 74% (95% CI 63-83) and 71% (95% CI 60-80), respectively, for ulcerative colitis. The validity of register-based definitions of childhood-onset IBD in the Swedish NPR is high and can be used to identify patients in observational research.

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© 2022 Mouratidou et al.

Déclaration de conflit d'intérêts

Olén has been PI on projects at Karolinska Institutet partly financed by investigator-initiated grants from Janssen, Ferring, Takeda, AbbVie, and Pfizer. None of those studies have any relation to the present study. Karolinska Institutet has received fees for Olen’s lectures and participation on advisory boards from Janssen, Ferring, Takeda, and Pfizer regarding topics not related to the present study. Ludvigsson coordinates a study unrelated to the present study on behalf of the Swedish IBD Quality Register (SWIBREG). That study has received funding from Janssen. Fagerberg has received consulting fees to the institution from Ferring Läkemedel AB, Adacyte Therapeutics S.L. and Index Pharmaceuticals AB and payment for lectures to the institution from Abigo Medical. The authors report no other conflicts of interest in this work.