Diagnostic Accuracy of Fecal Immunochemical Test in Patients at Increased Risk for Colorectal Cancer: A Meta-analysis

Abstract

Importance: The potential role of the fecal immunochemical test (FIT) for screening patients at increased risk for colorectal cancer (CRC) has not yet been elucidated.

Objective: To assess the diagnostic accuracy of FIT for CRC or advanced neoplasia (AN) in asymptomatic patients at above-average risk.

Data sources: MEDLINE, EMBASE, Cochrane Library, and gray literature sources through August 2016.

Study selection: Diagnostic studies evaluating the accuracy of FIT for CRC or AN in patients with a personal or familial history of CRC using colonoscopy as the reference standard.

Data extraction and synthesis: Two authors (A.K. and P.P.) independently extracted data and evaluated study quality using the Quality Assessment of Diagnostic Accuracy Studies-2 tool, and evaluated the quality of the body of evidence by means of GRADE (Grading of Recommendations Assessment, Development, and Evaluation). Hierarchical models were used to synthesize available evidence.

Main outcomes and measures: The primary outcome was the diagnostic performance of FIT for detecting CRC or AN.

Results: We included 12 studies (6204 participants). Seven studies were deemed at high or unclear risk of bias. The average sensitivity of FIT for CRC was 93% (95% CI, 53%-99%), and the average specificity was 91% (95% CI, 89%-92%), yielding a positive likelihood ratio (LR+) of 10.30 (CI 7.7-13.9) and a negative likelihood ratio (LR-) of 0.08 (95% CI, 0.01-0.75) (GRADE: very low). The average sensitivity of FIT for AN was 48% (95% CI, 39%-57%); and the average specificity was 93% (95% CI, 91%-94%), yielding an LR+ of 6.55 (95% CI, 5.0-8.5) and an LR- of 0.57 (95% CI, 0.48-0.67) (GRADE: very low). Subgroup analyses indicated that FIT cutoff values between 15- and 25-μg/g feces provided the best combination of sensitivity and specificity for the diagnosis of CRC (93% and 94%, respectively). Quantitative and 1-sample FIT showed adequate test performance, but data on other FIT brands and multiple samples were insufficient.

Conclusions and relevance: The FIT has high overall diagnostic accuracy for CRC but moderate accuracy for AN in patients at above-average personal or familial risk. Heterogeneity and wide confidence intervals limit the trustworthiness of our findings.

Figure 1.. PRISMA Flow Diagram

A search of MEDLINE, EMBASE, the Cochrane Library, and gray literature sources identified 3026 records. After deduplication, 2154 titles and abstracts were screened and 1952 records were rejected or deemed ineligible. The full text of the remaining 202 reports were assessed, and 12 studies met the inclusion criteria and were included in the systematic review. DARE indicates Database of Abstracts of Reviews of Effects.

Figure 2.. Sensitivity Estimates of Colorectal Cancer and Advanced Neoplasia

Forest plots demonstrate a high degree of heterogeneity for sensitivity estimates for (A) colorectal cancer and (B) advanced neoplasia. FN indicates false-negative results; FP, false-positive results; TN, true-negative results; TP, true-positive results.