Has there been a change in the natural history of Crohn's disease? Surgical rates and medical management in a population-based inception cohort from Western Hungary between 1977-2009.

Objectives: Medical therapy for Crohn's disease (CD) has changed significantly over the past 20 years with increasing use of immunosuppressives. In contrast, surgery rates are still high and there is little evidence that disease outcomes for CD have changed over the past decades. The objective of this study was to analyze the evolution of the surgical rates and medical therapy in the population-based Veszprem province database.

Methods: Data of 506 incident CD patients were analyzed (age at diagnosis: 31.5 years, s.d. 13.8 years). Both hospital and outpatient records were collected and comprehensively reviewed. The study population was divided into three groups by the year of diagnosis (cohort A: 1977-1989, cohort B: 1990-1998 and cohort C: 1999-2008).

Results: Overall, azathioprine (AZA), systemic steroid, and biological (only available after 1998) exposure was 45.8, 68.6, and 9.5%, respectively. The 1- and 5-year probability of AZA use were 3.2 and 6.2% in cohort A, 11.4 and 29.9% in cohort B, and 34.8 and 46.2% in cohort C. In a multivariate Cox-regression analysis, decade of diagnosis (P < 0.001, hazard ratio (HR)(cohorts B-C): 2.88-6.53), age at onset (P = 0.008, HR: 1.76), disease behavior at diagnosis (P < 0.001, HR(complicated): 1.76-2.07), and need for systemic steroids (P < 0.001, HR: 2.71) were significantly associated with the time to initiation of AZA therapy. Early AZA use was significantly associated with the time to intestinal surgery in CD patients; in a multivariate Cox analysis (HR: 0.43, 95% confidence interval (CI): 0.28-0.65) and after matching on propensity scores for AZA use (HR: 0.42, 95% CI: 0.26-0.67).

Conclusions: This population-based inception cohort has shown that the recent reduction in surgical rates was independently associated with increased and earlier AZA use.