Changes in inflammatory bowel disease subtype during follow-up and over time in 44,302 patients

Abstract

Aim: To investigate inflammatory bowel disease (IBD) register-based subtype classifications over a patient's disease course and over time. Methods: We examined International Classification of Diseases coding in patients with !2 IBD diagnostic listings in the National Patient Register 2002Register -2014. Results: 18% of the patients changed diagnosis (17% of adults, 29% of children) during a median follow-up of 3.8 years. Of visits with diagnoses of Crohn's disease (CD) or ulcerative colitis (UC), 97% were followed by the same diagnosis, whereas 67% of visits with diagnosis IBD-unclassified (IBD-U) were followed by another IBD-U diagnosis. Patients with any diagnostic change changed mostly once (47%) or twice (31%), 39% from UC to CD, 33% from CD to UC and 30% to or from IBD-U. Using a classification algorithm based on the first two diagnoses ('incident classification'), suited for prospective cohort studies, the proportion adult patients with CD, UC, and IBD-U 2002-2014 were 29%, 62%, and 10% (43%, 45%, and 12% in children). A classification model incorporating additional information from surgeries and giving weight to the last 5 years of visits ('prevalent classification'), suited for description of a study population at end of follow-up, classified 31% of adult cases as CD, 58% as UC and 11% as IBD-U (44%, 38%, and 18% in children). Conclusions: IBD subtype changed in 18% during follow-up. The proportion with CD increased and UC decreased from definition at start to end of follow-up. IBD-U was more common in children.

Inflammatory bowel disease and pancreatic cancer: a Scandinavian register‐based cohort study 1969‐2017

“…We requested either ≥2 records of IBD in the National Patient Registers 38 or ≥1 record of IBD in the National Patient Registers plus a colorectal biopsy record suggestive of IBD from the Swedish ESPRESSO Biopsy Register or the Danish Pathology Register 39 . The IBD subtype definition was based on the first two diagnostic listings, and patients with listings of both Crohn's disease and ulcerative colitis, or a listing of IBD unclassified (IBD‐U) were defined as IBD‐U, and included in the IBD group 40 …”

Adult height in patients with childhood‐onset inflammatory bowel disease: a nationwide population‐based cohort study

“…Finally, patients who had a diagnostic or procedure code typical of CD (Table S4) were classified as CD. The directions of reclassifications during the IBD disease course have been described previously …”

<p>Work Loss in Relation to Pharmacological and Surgical Treatment for Crohn’s Disease: A Population-Based Cohort Study</p>

“…Working-age (19 to 59 years) patients with Crohn's disease were identified through the Patient Register requiring that the first 2 diagnoses of IBD were Crohn's disease (K50) 19 and occurred between July 1st 2006 and Sep 30th 2013. The time period was chosen to ensure at least 1 year of lookback in the Prescribed Drug Register and a minimum follow-up of 2 years for all participants (work loss data available until Sep 30th 2015).…”

“…The net number of lost workdays due to sick leave and/or disability pension per time unit (month or year) was calculated by multiplying the number of days by the proportion of compensation received. 19…”