https://orcid.org/0000-0003-2301-298X
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Abstract
Purpose
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.
Methods
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.
Results
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.
Conclusion
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.
Study Report Guideline
The study is presented according to the recommendation in the STROBE statement on how to report observational studies in epidemiology. STROBE checklist for cohort-studies was used.
Abbreviations
IBD, Inflammatory bowel disease; UC, Ulcerative Colitis; CD, Crohn’s disease; IBDU, IBD unclassified; PPV, Positive predictive value; CI, Confidence interval.
Data Sharing Statement
No additional data are available because of Swedish regulations.
Acknowledgments
The SWIBREG study group consists of the following researchers:
Malin Olsson1, Pär Myrelid1, Henrik Hjortswang2, Jonas Bengtsson3, Hans Strid4, Marie Andersson4, Susanna Jäghult5, Michael Eberhardson2 Caroline Nordenvall7,8, Jan Björk9,10, Martin Rejler14,15, Olof Grip16, Pontus Karling17, and Jonas Halfvarson18. 1Department of Surgery, County Council of Östergötland and Department of Clinical and Experimental Medicine, Linköping University, Linköping Sweden; 2Department of Gastroenterology, County Council of Östergötland and Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden; 3Department of Surgery, Sahlgrenska University Hospital/Östra, Gothenburg, Sweden; 4Department of Internal Medicine, Södra Älvsborgs Hospital, Borås, Sweden; 5Stockholm Gastro Center, Karolinska Institutet, Stockholm, Sweden; 6Department of Medicine, Karolinska Institutet, Stockholm, Sweden; 7Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden; 8Department of Colorectal Cancer Karolinska University Hospital, Stockholm, Sweden; 9 Unit of Internal Medicine, Institute Medicine Solna, Karolinska Institutet, Stockholm, Sweden; 10 Patient Area Gastroenterology, Dermatovenerology and Rheumatology, Inflammation and Infection Theme Karolinska University Hospital, Stockholm, Sweden; 14Department of Medicine, Höglandssjukhuset Eksjö, Region Jönköping County Council, Jönköping, Sweden; 15Jönköping Academy for Improvement of Health and Welfare, Jönköping University, Jönköping, Sweden; 16Department of Gastroenterology, Skåne University Hospital, Malmö, Sweden; 17Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden; 18 Department of Gastroenterology, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
Author Contributions
All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.
Disclosure
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.