Risk of Age-related and Disease-related Complications and Mortality in Elderly-onset Inflammatory Bowel Disease - A Population-based Study.

Background & Aims: In this nationwide cohort from Israel (Epi-IIRN), we aimed to characterize risks for age-related complications, mortality, and inflammatory bowel disease (IBD)-related surgeries in patients with elderly-onset IBD (EO-IBD).

Methods: Data of patients with EO-IBD (≥65 years) diagnosed during 2005 to 2020 were retrieved from the epi-IIRN database. Patients with EO-IBD were compared with 3 age-, sex-, and district-matched non-IBD individuals, for age-related outcomes. Patients with incident EO-IBD were matched to 4 adult-onset (AO) IBD (≥18-65 years) by IBD subtype, sex, and district. Cumulative incidence functions were calculated to estimate event probabilities over time, accounting for death as a competing risk. Proportional subdistribution hazards models were used to assess predictors of medication use, surgery, and complications.

Results: Of 2826 EO-IBD cases, 2162 had 3 matched non-IBD controls. Mortality rates per 1000 person-years (PY) were similar in EO-IBD and non-IBD controls (292.32; 95% confidence interval [CI], 273.53-311.85 vs 291.24; 95% CI, 280.31-302.42, respectively) as were mortality causes and risk for pneumonia (adjusted hazard rate [aHR], 1.04; 95% CI, 0.84-1.29), fractures (aHR, 1.03; 95% CI, 0.82-1.29), bacteremia (aHR, 2.16; 95% CI, 0.87-5.40), and thromboembolism (aHR, 0.58; 95% CI, 0.27-1.23). When matching 2826 patients with EO-IBD to 11,304 patients with AO-IBD, the EO-IBD group had lower exposure to thiopurines (aHR, 0.44; 95% CI, 0.39-0.49) and anti-tumor necrosis factor (TNF) (aHR, 0.37; 95% CI, 0.32-0.42) and higher risk for abdominal surgery (aHR, 1.23; 95% CI, 1.04-1.46) in Crohn's disease [CD]; aHR, 1.51; 95% CI, 2.04-3.08 in ulcerative colitis [UC], respectively) but lower perianal surgery risk (hazard ratio [HR], 0.27; 95% CI, 0.16-0.47) in CD. The calculated frequencies of repeat perianal and abdominal surgery in the EO-CD and AO-CD groups at 3 years were 7.1% and 36%, respectively, and 29% and 21%, respectively.

Conclusions: Compared with non-IBD elderly, patients with EO-IBD have similar risks for death and complications. Compared with AO-IBD, patients with EO-IBD are at higher risk for abdominal surgery, but not for perianal surgery.