Regional differences in anti-TNF- therapy and surgery in the treatment of inflammatory bowel disease patients: a Norwegian nationwide cohort study

Background and aims: During the last decades, substantial progress has been made in both medical and surgical treatment of inflammatory bowel disease (IBD). The aim of this study was to determine the use of anti-TNFs and surgery during the first 3 years after diagnosis in IBD patients across the four health regions in Norway using nationwide patient registry data.Methods: This study used nationwide data from the Norwegian Patient Registry. Cumulative incidence of anti-TNF exposure and major surgery was calculated for patients diagnosed in 2010-2012. The analyses were stratified by diagnosis and health region. All patients were followed for an equal period of 3 years from diagnosis.Results: The study population included 8,257 IBD patients first registered between 2010 and 2012, of whom 2,829 were diagnosed with Crohn's disease (CD) and 5,428 with ulcerative colitis (UC). Across Norway's health regions, the cumulative incidence of major surgery after 3 years varied from 11.4% to 17.1% for CD and from 4.6% to 6.9% for UC. The cumulative incidence of anti-TNF exposure varied from 20.9% to 31.4% for CD and from 8.0% to 13.5% for UC. The region with the lowest anti-TNF use had the highest surgery rates for both UC and CD.Conclusions: Cumulative incidence of anti-TNF exposure and surgery varied significantly across Norway's health regions during the three first years after IBD diagnosis.