Influence of Comorbidities on Colorectal Cancer Screening Participation and Mortality

Organized screening programs improve colorectal cancer (CRC) screening participation, but outreach services can be improved. We sought to understand screening deferral by examining patient-level factors and how they relate to fecal immunochemical test (FIT) orders, completion rates, and long-term mortality.

Patients aged 50-75 years who were not up to date with CRC screening receiving usual care were followed over time (NCT02613260). Patient-level laboratory and cancer registry data were used to identify patients who met a specified laboratory threshold: albumin < 3 g/dL, HIV viral load > 10,000 copies or CD4 < 200 cells/µL, creatinine > 4 mg/dL, platelets < 100,000/µL, total bilirubin > 4 µmol/L, NH3 > 20, positive urine amphetamine or cocaine, serum ethanol > 80, hemoglobin A1C > 10%, and stage 3 or 4 cancer. The proportion of patients with a FIT order, FIT completion in 1-year, and mortality at 8-years were compared in patents with and without the lab abnormality.

Nine thousand six hundred seventy-six patients were eligible for screening, of which 1053 met the criteria for laboratory abnormalities. Patients with laboratory abnormalities were less likely to have a FIT order placed (39.5% vs 66.8%, P < .001) and were less likely to complete FIT screening (21.5% vs 51.6%, P < .001). Moreover, patients with laboratory abnormalities experienced higher mortality at 8-year follow-up (32.6% vs 6.7%, P < .001).

Patients with laboratory abnormalities were less likely to have a FIT order placed and completed, and experienced higher mortality, suggesting that screening was deferred by providers. Future studies should gather provider input to understand how patient-level electronic data could be considered in the implementation of screening services.