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.