Objective: We provide new information about how the risk of adverse events following colonoscopy varies by age and indication (screening vs. follow-up performed to evaluate a positive result from another screening modality).
Methods: We constructed a retrospective cohort comprised of 43,456 individuals aged 40-85 years enrolled in a large integrated healthcare organization in Washington State who underwent outpatient colonoscopy between 1994 and 2009. We calculated rates of serious adverse events (perforation, hemorrhage, and acute diverticulitis) in the 30 days following colonoscopy and compared rates using log-binomial regression models.
Results: We observed 4.7 serious adverse events per 1,000 screening colonoscopies and 6.8 per 1,000 follow-up colonoscopies. Polypectomy increased the rate of serious adverse events (relative rate [RR], 2.64; 95% confidence interval [CI], 1.97-3.56). Older age was associated with increased risk of serious adverse events, after adjusting for polypectomy, gender, and indication. Compared to individuals aged 50-64 years, risk was elevated for those aged 65-74 (RR, 1.93; 95% CI, 1.40-2.65) and 75-85 (RR, 3.21; 95% CI 2.14-4.86). We observed similar age effects in individuals with and without significant comorbid conditions.
Conclusions: The risks of serious adverse events following colonoscopy performed as part of screening are low but increase with age and are more likely after polypectomy.