To Örebro University

Biological therapy has emerged as an important treatment modality for inflammatory bowel disease (IBD). Despite the prevailing trend, there contin­ues to be a lack of guidelines for selecting a suitable biological drug for a specific patient group. Register data are valuable sources for real-world studies of treatment outcomes across diverse patient groups. This thesis in­cludes four observational cohort studies assessing clinical and therapeutic aspects of biological treatment in patients with IBD, covering the main sub­types Crohn's disease and ulcerative colitis. The overarching aim is to ad­vance understanding of the effectiveness and safety of biological treatment in patients diagnosed with IBD.

Study I examined anti-tumour necrosis factor (anti-TNF) drug continuation rates in 955 patients with IBD that were recorded in the Swedish IBD regis­ter (SWIBREG). Infliximab (vs adalimumab) discontinuation was higher when used as first- and second-line treatment in patients with Crohn's dis­ease. Study II examined the use of golimumab in ulcerative colitis. Most (70%) of the 50 study patients were previously exposed to anti-TNF. After 1 year, 23 (46%) patients were still on golimumab treatment and improve­ments in clinical and biochemical markers were seen. Study III investigated long-term outcomes of vedolizumab treatment in patients participating in the extension of the Swedish observational study on vedolizumab, focusing on its effectiveness and use of healthcare resources in patients with IBD (SVEAH). Patients who initially responded to vedolizumab treatment and continued it beyond 1 year experienced high rates of clinical remission and improved quality of life measures after 3 years. Few serious adverse events were reported. Study IV examined correlations between baseline clinical characteristics, serum proteins, and drug levels post-induction. Four pro­teins of interest correlated with s-adalimumab levels.

This thesis proposes that the clinical and biochemical characterisation of patients with IBD can contribute to informed decision-making in biological treatment.