Epidemiology and Natural History of Elderly-onset inflammatory bowel disease: Results from a territory-wide Hong Kong IBD registry.

BACKGROUND Elderly-onset inflammatory bowel disease (IBD), defined as age ≥60 at diagnosis, is increasing worldwide. We aimed to compare clinical characteristics and natural history of elderly-onset IBD patients to adult-onset IBD patients. METHODS Patients with a confirmed diagnosis of IBD from 1981 to 2016 were identified from a territory-wide Hong Kong IBD registry involving 13 hospitals. Demographics, comorbidities, clinical features and outcomes of elderly-onset IBD patients were compared to adult-onset IBD patients. RESULTS A total of 2413 patients were identified, of whom 270 (11.2%) had elderly-onset IBD. Median follow-up duration was 111 months (Interquartile range [IQR]: 68-165 months). Ratio of ulcerative colitis (UC): Crohn's disease (CD) was higher in elderly-onset IBD than adult-onset IBD patients (3.82:1 vs. 1.39:1; p&0.001). Elderly-onset CD had less perianal involvement (5.4% vs. 25.4%; p&.001) than adult-onset. Elderly-onset IBD patients had significantly lower cumulative use of immunomodulators (p=0.001) and biologics (p=0.04). Elderly-onset IBD was associated with higher risks of cytomegalovirus colitis (Odds ratio [OR]: 3.07; 95% Confidence Interval (CI) 1.92-4.89; p&0.001); herpes zoster (OR: 2.42; 95% CI: 1.22-4.80; p=0.12) and all cancer development (Hazard ratio: 2.97; 95% CI: 1.84-4.79; p&0.001). They also had increased number of overall hospitalization (OR: 1.14; 95% CI 1.09-1.20; p&0.001), infections-related hospitalization (OR: 1.87; 95% CI 1.47-2.38; p&0.001) and IBD-related hospitalization (OR: 1.09; 95% CI: 1.04- 1.15; p=0.001) compared to adult-onset IBD. CONCLUSION Elderly-onset IBD patients were associated with increased risk of infections, cancer development and increased infections- and IBD-related hospitalizations. Specific therapeutic strategies to target this special population is needed.