Discrepancies in Fecal Occult Blood Test RESULTS in Hospitalized Patients

Introduction: Fecal occult blood test (FOBT) is a validated screening test for colorectal cancer (CRC) in the outpatient setting. However, it is frequently and inappropriately used as a diagnostic tool in the inpatient setting despite a lack of supporting evidence for its use. We aim to determine the clinical utility of the FOBT in hospitalized patients, with specific focus on the relationship between FOBT results and the number of endoscopies, endoscopic findings, and interventions performed. Methods: Retrospective chart review of inpatients who underwent Guaiac-FOBT at a community hospital from 2016-2019. Patient demographics, FOBT indications, ordering providers, and the effect of FOBT results on rates of endoscopy and intervention were assessed. Categorical data were summarized as frequency (N) and percentage (%) and compared using X2 or Fisher’s exact test. Continuous data were summarized as Mean (SD) or Median (Q1, Q3), and compared using Student’s T-test or Kruskal-Wallis. Results: A total of 987 patients were identified, 55% had a positive FOBT. The mean age of patients with positive and negative FOBT results were 74 and 72, respectively. Majority (55%) were female. Majority (61%) were White, 21% Black, and 14% Hispanic. Hospitalists ordered the most FOBTs compared to the emergency department or other specialties (51% vs 40% vs 9%, P < 0.001). Anemia [other than iron-deficiency anemia (IDA)] was the most common indication (61%) for testing and these patients were more likely to have a negative FOBT(P < 0.001). FOBT was more likely to be positive if ordered for overt upper gastrointestinal (GI) bleeding (melena and hematemesis, P < 0.001). Despite a negative FOBT, endoscopy was performed in 54% of patients referred to the GI service compared with 71% of patients with positive FOBTs. Those with negative FOBT had a median of 1 lesion compared with a median of 2 lesions in the FOBT positive group (P = 0.4269). There was no difference in the endoscopic findings between the two groups (P = 0.722) and no difference in number of interventions performed (Table 1). Conclusion: This study underscores the inconsistent diagnostic yield of the FOBT in hospitalized patients. Positive results generated more procedures but there was no significant difference in the type of pathology found, the number of lesions, or the intervention performed when compared with patients with negative FOBT. The use of FOBT in the inpatient setting increases healthcare spending without affecting the overall clinical course or outcome.Table 1.: Endoscopic Intervention by FOBT Result.