Declining Trends of Reoperations and Disease Behaviour Progression in Crohn's Disease over Different Therapeutic Eras-A Prospective, Population-Based Study from Western Hungary between 1977-2020, Data from the Veszprem Cohort.

Background and aims: Few population-based studies have investigated long-term surgery rates for Crohn's disease [CD]. Our aim was to analyse disease progression and surgery rates in a population-based cohort over different therapeutic eras, based on the time of diagnosis: cohort-A [1977-1995], cohort-B [1996-2008], and cohort-C [2009-2018].

Methods: A total of 946 incident CD patients were analysed (male/female: 496/450; median age at diagnosis: 28 years [y]; interquartile range [IQR]: 22-40]). Patient inclusion lasted between 1977 and 2018. Immunomodulators have become widespread in Hungary since the mid-1990s and biologic therapies since 2008. Patients were followed prospectively, with both in-hospital and outpatient records reviewed regularly.

Results: The probability of disease behaviour progression from inflammatory [B1] to stenosing or penetrating phenotype [B2/B3] significantly decreased (27.1 ± 5.3%/21.5 ± 2.5%/11.3 ± 2.2% in cohorts A/B/C, respectively, after 5 years; 44.3 ± 5.9%/30.6 ± 2.8%/16.1 ± 2.9% after 10 years, respectively; [pLogRank <0.001]). The probability of first resective surgery between cohorts A/B/C were 33.3 ± 3.8%/26.5 ± 2.1%/28.1 ± 2.4%, respectively, after 5 years; 46.1 ± 4.1%/32.6 ± 2.2%/33.0 ± 2.7% after 10 years, respectively; and 59.1 ± 4.0%/41.4 ± 2.6% [cohorts A/B] after 20 years. There was a significant decrease in first resective surgery risk between cohorts A and B [plog rank = 0.002]; however, no further decrease between cohorts B and C [plog rank = 0.665]. The cumulative probability of re-resection in cohorts A/B/C was decreasing over time (17.3 ± 4.1%/12.6 ± 2.6%/4.7 ± 2.0%, respectively, after 5 years [plog rank = 0.001]).

Conclusion: We report a continuous decline in reoperation rates and disease behaviour progression in CD over time, with the lowest values in the biologic era. In contrast, there was no further decrease in the probability of first major resective surgery after the immunosuppressive era.