UCSF

Background

Performance characteristics of fecal immunochemical tests (FITs) to screen for colorectal cancer (CRC) have been inconsistent.

Purpose

To synthesize data about the diagnostic accuracy of FITs for CRC and identify factors affecting its performance characteristics.

Data sources

Online databases, including MEDLINE and EMBASE, and bibliographies of included studies from 1996 to 2013.

Study selection

All studies evaluating the diagnostic accuracy of FITs for CRC in asymptomatic, average-risk adults.

Data extraction

Two reviewers independently extracted data and critiqued study quality.

Data synthesis

Nineteen eligible studies were included and meta-analyzed. The pooled sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of FITs for CRC were 0.79 (95% CI, 0.69 to 0.86), 0.94 (CI, 0.92 to 0.95), 13.10 (CI, 10.49 to 16.35), 0.23 (CI, 0.15 to 0.33), respectively, with an overall diagnostic accuracy of 95% (CI, 93% to 97%). There was substantial heterogeneity between studies in both the pooled sensitivity and specificity estimates. Stratifying by cutoff value for a positive test result or removal of discontinued FIT brands resulted in homogeneous sensitivity estimates. Sensitivity for CRC improved with lower assay cutoff values for a positive test result (for example, 0.89 [CI, 0.80 to 0.95] at a cutoff value less than 20 µg/g vs. 0.70 [CI, 0.55 to 0.81] at cutoff values of 20 to 50 µg/g) but with a corresponding decrease in specificity. A single-sample FIT had similar sensitivity and specificity as several samples, independent of FIT brand.

Limitations

Only English-language articles were included. Lack of data prevented complete subgroup analyses by FIT brand.

Conclusion

Fecal immunochemical tests are moderately sensitive, are highly specific, and have high overall diagnostic accuracy for detecting CRC. Diagnostic performance of FITs depends on the cutoff value for a positive test result.

Primary funding source

National Institute of Diabetes and Digestive and Kidney Diseases and National Cancer Institute.