ASPO Abstracts
Diagnostic performance of four fecal immunochemical tests for detecting advanced colorectal neoplasia: preliminary results
Category: Early Detection & Risk Prediction
Conference Year: 2019
Abstract Body:
Background. Screening programs based on fecal blood testing have been shown in randomized controlled trials to reduce colorectal cancer incidence and mortality. Professionalorganizations highly recommend screening average-risk patients with fecal immunochemical testing (FIT). Many patients find these stool tests more acceptable than colonoscopy and stool testing may be the preferred option for areas with limited endoscopic resources. However, the diagnostic performance of FIT testing, particularly for CLIA-waived point-of-care (POC) tests, hasnot been well studied. Purpose. We are comparing the diagnostic accuracy of 4 FIT tests, one automated (AUTO) and 3 POC, for detecting advanced neoplasia (advanced adenomas and carcinomas) using colonoscopy as a gold standard. Methods. We are enrolling subjects ages 50 to 85 at 3 academic medical centers in Iowa, Texas, and North Carolina who were scheduled for a screening or surveillance colonoscopy. Each subject completed 4 different FIT tests on asingle stool specimen. Based on colonoscopy results, we calculated sensitivity, specificity, and predictive values. We used PROC GLIMMIX models in SAS to compare sensitivity and specificity across the different tests, accounting for the within-patient correlation.Results. We currently have 641 subjects who completed FIT and colonoscopy. Mean age is 61.2 (±7.5) years, 63% women, 63% non-Hispanic white, and 31% Hispanic. We found advanced neoplasia, including 5 carcinomas, in 68 subjects. The sensitivities for detecting these neoplasia were 3%, 22%, 28%, and 16% (AUTO), respectively. Corresponding positive predictive values were 18%, 21%, 33%, and 24% (AUTO). Specificities was 97%, 89%, 90%, and 94% (AUTO), respectively, and corresponding negative predictive values were 89%, 91%, 92%, and 90% (AUTO). We found statistically significant differences in sensitivity (P <0.01) and specificity (P < 0.01) across tests. Conclusions. Early data suggest that FIT products mayvary in their sensitivity and specificity for detecting advanced colorectal neoplasia. Thisvariability could have important impacts on the effectiveness of efforts to limit the burden ofcolorectal cancer by increasing population-based screening rates through fecal blood testing.
Keywords: Colorectal cancer screeningFecal immunochemicaltestDiagnostic accuracy