Improvements in the Long-Term Outcome of Crohn's Disease Over the Past Two Decades and the Relation to Changes in Medical Management: Results from the Population-Based IBDSL Cohort.

Objectives: Medical treatment options and strategies for Crohn's disease (CD) have changed over the past decades. To assess its impact, we studied the evolution of the long-term disease outcome in the Dutch Inflammatory Bowel Disease South Limburg (IBDSL) cohort.

Methods: In total, 1,162 CD patients were included. Three eras were distinguished: 1991-1998 (n=316), 1999-2005 (n=387), and 2006-2011 (n=459), and patients were followed until 2014. Medication exposure and the rates of hospitalization, surgery, and phenotype progression were estimated using Kaplan-Meier survival analyses and compared between eras by multivariable Cox regression models. Second, propensity score matching was used to assess the relation between medication use and the long-term outcome.

Results: Over time, the immunomodulator exposure rate increased from 30.6% in the era 1991-1998 to 70.8% in the era 2006-2011 at 5 years. Similar, biological exposure increased from 3.1% (era 1991-1998) to 41.2% (era 2006-2011). In parallel, the hospitalization rate attenuated from 65.9% to 44.2% and the surgery rate from 42.9% to 17.4% at 5 years, respectively (both P<0.01). Progression to a complicated phenotype has not changed over time (21.2% in the era 1991-1998 vs. 21.3% in the era 2006-2011, P=0.93). Immunomodulator users had a similar risk of hospitalization, surgery, or phenotype progression as propensity score-matched nonusers (P>0.05 for all analyses). Similar results were found for biological users (P>0.05 for all analyses).

Conclusions: Between 1991 and 2014, the hospitalization and surgery rates decreased, whereas progression to complicated disease is still common in CD. These improvements were not significantly related to the use of immunomodulators and biologicals.