Diagnostic Indications and Endoscopic Correlates of Fecal Occult Blood Testing in Hospitalized Patients

Background: FOBT is widely used for colorectal cancer screening in asymptomatic populations but is frequently applied in hospitalized patients with anemia or suspected gastrointestinal bleeding despite limited supporting evidence. Objectives: To evaluate the clinical utility of fecal occult blood testing (FOBT) in hospitalized patients, focusing on its indications and its association with endoscopic findings while accounting for differential endoscopic verification. Methods: We conducted a retrospective study of 160 hospitalized adults who underwent FOBT at a medium-complexity referral center. Demographic, clinical, and endoscopic data were extracted from electronic medical records. Group comparisons used Wilcoxon rank-sum, chi-square, or Fisher's exact tests; multivariable logistic regression, verification-bias-corrected diagnostic accuracy (Begg-Greenes method), and multiple imputation assessed the association between FOBT and endoscopic findings. Results: FOBT was positive in 61.3% of patients. Anemia was the main indication (51%), followed by melena (26%) and hematochezia (6.9%). FOBT positivity was significantly associated with anemia at admission (82% vs. 68%, p = 0.044) and hematochezia (10% vs. 0%, p = 0.007). Endoscopic verification differed markedly by the FOBT result (71% vs. 29%), and no significant association between FOBT positivity and abnormal endoscopic findings persisted after multivariable adjustment or bias correction, for either EGD (OR 2.01, 95%CI 0.66-6.10) or colonoscopy (OR 4.58, 95%CI 0.39-54.3). Conclusions: FOBT shows no robust diagnostic association with endoscopic pathology, upper or lower, once differential verification is accounted for. Its main actionable finding was frequent guideline-discordant use in patients with overt bleeding, identifying institutional stewardship as the primary target for improving diagnostic efficiency in inpatient care.