Application of the Capture–recapture Method to Ascertain the Completeness of the Saxon Pediatric IBD Registry in Germany

Aim The incidence of inflammatory bowel disease (IBD) is increasing worldwide. The Saxon Pediatric IBD Registry was founded in 2000 to describe the epidemiology of pediatric IBD in Germany. The aim of this study was to determinate the completeness of this registry for children and adolescents younger than 15 years and to make this approach transparent. Results of this completeness update have broad implications for further scientific publications from the registry dataset. Method The capture–recapture method with two data sources was used to ascertain completeness. A second data source was collected in 2019 for the observation period 2008–2014 from all pediatricians, gastroenterologists, and internists working in practices in a predefined region in Saxony, Germany. Results A total of 23 patients with IBD were reported who fulfilled the inclusion criteria. One of them was not recorded in the registry. Therefore, the completeness of the registry was estimated at 95.7% (95% CI 90.2–100). Initial analysis of the Saxon Pediatric IBD Registry over the 15-year period 2000–2014 includes 532 patients, 312 (58.6%) male and 220 (41.4%) female. The distribution of single IBD diseases in the registry was as follows: Crohn’s disease 338 patients (63.5%), ulcerative colitis 176 patients (33.1%), and unclassified IBD 18 patients (3.4%). Evaluations by sex and by disease in age groups and by age at onset were tabulated. Conclusion This study demonstrates that the completeness level of the Saxon Pediatric IBD Registry is high (95.7%), and thus the epidemiological data of the registry are reliable.