Effect of Chronic Comorbidities on Follow-up Colonoscopy After Positive Colorectal Cancer Screening Results: A Population-Based Cohort Study

Fecal occult blood tests (FOBTs) are colorectal cancer screening tests used to identify individuals requiring further investigation with colonoscopy. Delayed colonoscopy after positive FOBT (FOBT+) is associated with poorer cancer outcomes. We assessed the effect of comorbidity on colonoscopy receipt within 12 months after FOBT+.Population-based healthcare databases from Ontario, Canada, were linked to assemble a cohort of 50-74-year-old individuals with FOBT+ results between 2008 and 2017. The associations between comorbidities and colonoscopy receipt within 12 months after FOBT+ were examined using multivariable cause-specific hazard regression models.Of 168,701 individuals with FOBT+, 80.5% received colonoscopy within 12 months. In multivariable models, renal failure (hazard ratio [HR] 0.71, 95% confidence interval [CI] 0.62-0.82), heart failure (HR 0.77, CI 0.75-0.80), and serious mental illness (HR 0.88, CI 0.85-0.92) were associated with the lowest colonoscopy rates, compared with not having each condition. The number of medical conditions was inversely associated with colonoscopy uptake (≥4 vs 0: HR 0.64, CI 0.58-0.69; 3 vs 0: HR 0.75, CI 0.72-0.78; and 2 vs 0: HR 0.87, CI 0.85-0.89). Having both medical and mental health conditions was associated with a lower colonoscopy uptake relative to no comorbidity (HR 0.88, CI 0.87-0.90).Persons with medical and mental health conditions had lower colonoscopy rates after FOBT+ than those without these conditions. Better strategies are needed to optimize colorectal cancer screening and follow-up in individuals with comorbidities.