Disease Outcome of Ulcerative Colitis in an Era of Changing Treatment Strategies: Results from the Dutch Population-Based IBDSL Cohort

Background and Aims: In the past decades, treatment options and strategies for ulcerative colitis [UC] have radically changed. Whether these developments have altered the disease outcome at population level is yet unknown. Therefore, we evaluated the disease outcome of UC over the past two decades in the South-Limburg area of The Netherlands. Methods: In the Dutch population-based IBDSL cohort, three time cohorts were defined: cohort 1991-1997 [cohort A], cohort 1998-2005 [cohort B], and cohort 2006-2010 [cohort C]. The colectomy and hospitalisation rates were compared between cohorts by Kaplan-Meier survival analyses. Hazard ratios [HR] for early colectomy [within 6 months after diagnosis], late colectomy [beyond 6 months after diagnosis], and hospitalisation were calculated using Cox regression models. Results: In total, 476 UC patients were included in cohort A, 587 patients in cohort B, and 598 patients in cohort C. Over time, an increase in the use of immunomodulators [8.1%, 22.8% and 21.7%, respectively, p < 0.01] and biological agents [0%, 4.3% and 10.6%, respectively, p < 0.01] was observed. The early colectomy rate decreased from 1.5% in cohort A to 0.5% in cohort B [HR 0.14; 95% confidence interval 0.04-0.47], with no further decrease in cohort C [0.3%, HR 0.98; 95% confidence interval 0.20-4.85]. Late colectomy rate remained unchanged over time [4.0% vs 5.2% vs 3.6%, respectively, p = 0.54]. Hospitalisation rate was also similar among cohorts [22.3% vs 19.5% vs 18.3%, respectively, p = 0.10]. Conclusion: Over the past two decades, a reduction in early colectomy rate was observed, with no further reduction in the most recent era. Late colectomy rate and hospitalisation rate remained unchanged over time.