Diagnostic Performance of Immunochemical versus Guaiac Fecal Occult Blood Tests in Symptomatic Cameroonian Patients Undergoing Colonoscopy: A Cross-Sectional Diagnostic Accuracy Study

Background Fecal occult blood testing (FOBT) stands as a fundamental, non-invasive diagnostic tool for detecting subtle gastrointestinal bleeding, a common indicator of colorectal cancer (CRC). CRC remains the second leading cause of cancer-related mortality globally. In Cameroon, despite CRC being the second most common digestive cancer, a national screening strategy is yet to be established. Among the available FOBT methods, the traditional guaiac-based fecal occult blood test (gFOBT) and the immunochemical fecal occult blood test (iFOBT) are predominant, with iFOBTs generally demonstrating superior diagnostic performance. Objective This study aimed to compare the diagnostic performance of Hemoccult® (gFOBT) and SD BIOLINE FOB® (iFOBT) for the detection of colorectal abnormalities, utilizing colonoscopy as the reference standard, in symptomatic adult patients referred for colonoscopy in healthcare facilities across Yaoundé and Douala, Cameroon. Methods A cross-sectional diagnostic accuracy study was conducted from November 2, 2021, to August 20, 2022, in four distinct health facilities. We enrolled adult patients, aged 21 years and older, presenting symptomatic indications for colonoscopy. Key diagnostic accuracy indicators—namely sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and Youden's Index—were meticulously assessed for both index tests against the definitive colonoscopy results concerning colorectal abnormalities. Results Out of 323 initially screened patients, 108 met the inclusion criteria and were included in the final analysis. SD BIOLINE FOB® identified occult blood in 45.37% of cases, while Hemoccult® yielded positive results in 31.48%. SD BIOLINE FOB® unequivocally demonstrated superior sensitivity (67.9%; 95% CI: 54.1–80.1%) compared to Hemoccult® (41.1%; 95% CI: 28.0–55.2%). Notably, both tests exhibited comparable specificity (78.8%; 95% CI: 66.0–88.7%). Furthermore, SD BIOLINE FOB® successfully identified a higher number of various colorectal abnormalities, including polyps and exophytic lesions. Conclusion The SD BIOLINE FOB® test exhibited better diagnostic performance than Hemoccult® in detecting colorectal abnormalities within this symptomatic Cameroonian patient cohort. While these findings underscore its promising utility as a diagnostic aid in resource-limited contexts, its broader role in population-based CRC screening necessitates further rigorous evaluation in asymptomatic cohorts, given the inherent spectrum bias in our study design.