Diagnostic accuracy of a single qualitative immunochemical fecal occult blood test coupled with physical measurements

Abstract

Background: We aimed to improve the sensitivity of immunochemical fecal occult blood test (I-FOBT) to screen colorectal neoplasm among average-risk adults.

Methods: This is a diagnostic cohort study. All health examination participants receiving a single qualitative I-FOBT and a screening colonoscopy from January 2010 to June 2011 were included. Stool specimens were collected for I-FOBT before colonoscopy. Using pathology as gold standard, significant colorectal neoplasm was defined as advanced adenoma or malignancy.

Results: A total of 1 007 health examinees were identified. Fifty-five (5.5%) had borderline positive (+/-) I-FOBT, while 38 (3.8%) had positive I-FOBT. Twenty-four (2.4%) had advanced adenoma, and five (0.5%) had carcinoma. Using borderline positive I-FOBT as cutoff value, the sensitivity and specificity for significant colorectal neoplasm were 34.5% (95% confidence interval (CI) 19.9%-52.7%) and 91.5% (95% CI 89.6%-93.1%), respectively. If combined with advanced age, high blood pressure (BP), and abdominal obesity, a fulfillment of either two criteria further increased the sensitivity to 72.4% (95% CI 54.3%-85.3%) with a specificity of 68.8% (95% CI 65.8%-71.6%).

Conclusion: The sensitivity of a single qualitative I-FOBT for the detection of significant colorectal neoplasm can be increased by coupling with age, BP, and abdominal obesity.