Karoline Anisdahl[1,2], Sandre S. Lirhus[3], Asle W. Medhus[1], Bjørn Moum[1,2], Hans Olav Melberg[3,4], Marte L. Høivik[1,2]

Affiliates

Oslo University Hospital, Department of Gastroenterology, Oslo, Norway[1], University of Oslo, Institute of Clinical Medicine, Oslo, Norway[2], University of Oslo, Department of Health Management and Health Economics, Oslo, Norway[3], University of Tromsø, Department of Community Medicine, Tromsø, Norway[4]

Abstract

Background: We have previously reported regional differences in biological and surgical treatment for IBD patients diagnosed from 2010 to 2012 (1). In this study, our aim was to explore whether regional differences in the use of biologics and surgery were consistent over time.

Methods: We performed a nationwide, observational study using linked data from the Norwegian Patient Registry (NPR) and the Norwegian Prescription Database (Nor-PD). Incident cases were defined as ≥2 IBD diagnosis codes in the NPR, or ≥1 IBD diagnosis code in the NPR and ≥2 IBD prescriptions in the NorPD. Kaplan-Meier estimates were used to calculate time from diagnosis to first biological and/or major surgical event. The log-rank test was used to test for statistical significance. Patients were stratified by health region affiliation (Northern, Central, Western and South-Eastern), and grouped as Cohort I (2011–2014) or Cohort II (2015–2019) depending on year of diagnosis.

Results: We included 7306 patients with Crohn’s disease (CD) and 13703 patients with ulcerative colitis (UC). Results are shown in Figure 1.
The proportion of IBD patients receiving biologics increased from Cohort I to Cohort II in all regions. For CD, the difference between the Northern and Western region became significant in Cohort II (p=0.01). For UC, the proportion receiving biologics were higher in the South-Eastern region (p≤0.01) in Cohort I and lower in the Central region (p≤0.01) in Cohort II. The proportion of CD patients undergoing surgery decreased from Cohort I to Cohort II, and the regional differences decreased as well. For UC patients, the regional differences remained, and the Central region had the highest proportion of patients undergoing surgery in both Cohorts (p≤0.02).

Conclusions: The study revealed important, sustained regional differences in the use of both biologics and surgery, especially for UC. Pursuing whether geographical treatment variation impacts outcome will aid in ensuring equal access to best clinical care.

References
1. Lirhus SS, Hoivik ML, Moum B, Melberg HO. Regional differences in anti-TNF-alpha therapy and surgery in the treatment of inflammatory bowel disease patients: a Norwegian nationwide cohort study. Scandinavian journal of gastroenterology. 2018;53(8):952-957.