P793 Prevalence and phenotype of inflammatory bowel disease across primary and secondary care: Implications for colorectal cancer surveillance

Abstract

Patients diagnosed with inflammatory bowel disease (IBD) with colonic involvement have increased risk of colorectal cancer (CRC). Colonoscopic surveillance reduces the risk of CRC-associated death through early detection; national/international guidelines recommend chromoendoscopy. We aimed to assess the burden of IBD in primary care unknown to our service and to identify patients eligible for, but not being offered, surveillance. We conducted a population-based observational study across primary and secondary care to evaluate the incidence and prevalence of IBD in our catchment area. Cases were identified from primary care using searches of practice databases and in secondary care using searches of electronic hospital records. Case inclusion required a specialist diagnosis of ulcerative colitis (UC), Crohn’s disease (CD) or IBD unclassified and confirmatory evidence (specialist correspondence, histology, endoscopic or operative findings). IBD was phenotyped according to the Montreal Classification and patients under the age of 75 years, who had been diagnosed with IBD with colonic disease involvement for more than 10 years, were deemed eligible for colonoscopic surveillance. Patients from 48/49 GP practices within our catchment area were included. We identified 2816 patients with IBD living within our catchment of which 11% (309/2816) were unknown to any local secondary care service. Overall, UC prevalence was 435/100000 people (95% confidence interval 416–456), Crohn’s disease prevalence was 231/100000 (95% CI 216–246), and IBD unclassified prevalence was 31/100000 (95% CI 26–37). Patients managed solely in primary care, compared with those in secondary care, were older (median age [IQR] 63.2 [50.7–72.3] vs 54.2 [40–68.1] years, p < 0.0001) and had longer disease duration (median [IQR] 23.3 [13.6–36.7] vs 11.6 [5.6–20.6] years, p < 0.0001). The proportion of UC out of total IBD was higher in primary care (73% [227/309] vs. 61% [1531/2507], p < 0.0001). A higher proportion of IBD patients in primary care than secondary care had undergone a colectomy (17% [54/309] vs 28% [148/2507], p < 0.0001). Overall, 16% (393/2507) patients known to secondary care and 30% (92/309) of patients unknown to any secondary care services were eligible for colonoscopic surveillance, equivalent to approximately one colonoscopy list per week. We report one of the highest prevalence rates of IBD in Western Europe (1 in 143 patients). 11% of patients living in our immediate catchment area were unknown to our service; a third of these were eligible for colonoscopic colorectal cancer surveillance. Effective colorectal cancer surveillance programmes in IBD must target primary-care populations and not just known secondary care populations.