Clinical Diagnosis Codes Identify Patients Unlikely to Receive Orders for Fecal Immunochemical Tests

IntroductionAutomated colorectal cancer (CRC) screening programs often invite all age-eligible patients for fecal immunochemical testing (FIT), but providers may defer screening in clinically complex patients. However, such nuanced decisions are not captured by most automated systems. We evaluated whether International Classification of Diseases, Tenth Revision (ICD-10) codes are associated with variations in FIT ordering patterns beyond age-based outreach criteria.MethodsIn a retrospective observational study of 15,020 screening-eligible patients aged 50-75, we compared the frequency of ICD-10 codes between patients with and without a FIT order. We repeated the analysis restricted to those with a Charlson Comorbidity Index (CCI)<5.ResultsOverall, 4,833 (32.2%) patients did not have a FIT order. Of the 1,215 ICD-10 codes examined, 96 were significantly associated with the absence of a FIT order (p<0.05). These codes frequently indicated digestive diseases (e.g., colonic neoplasm, diverticular disease), advanced comorbidities (e.g., frailty, paralysis), and acute conditions (e.g., fractures, severe infections). Among the patients with CCI<5, 41 codes were associated with the absence of a FIT order (p<0.05), such as heart failure and chronic kidney disease.ConclusionScreening-eligible patients without a FIT order were more likely to have ICD-10 codes reflecting digestive diseases, chronic comorbidities, and acute conditions. These findings demonstrate that specific diagnostic profiles are associated with real-world FIT ordering patterns, highlighting the need for further investigation into how comorbidities and competing clinical priorities relate to CRC screening decisions.