Dataset Information

Direct comparison of ten quantitative fecal immunochemical tests for hemoglobin stability in colorectal cancer screening.

ABSTRACT:

Objectives

To systematically investigate and directly compare, for the first time, the sample stability of a large number of quantitative fecal immunochemical tests (FITs) at different storage conditions.

Methods

Stool samples were obtained from participants of the German screening colonoscopy program between 2005 and 2010. After an initial FIT-based hemoglobin (Hb) measurement, stool samples were kept frozen at -80 °C until analysis. Twenty randomly selected participants with initial measurements ranging from 10 to 100 μg Hb/g feces were included. Ten quantitative FITs were investigated in parallel. A defined stool amount was extracted using each manufacturer's brand-specific fecal sampling device and stored at 5 °C, 20 °C, and 35 °C, respectively. After 1, 4, 5, and 7 days, the samples were analyzed blinded. Median fecal Hb concentrations and positivity rates were calculated.

Results

Mean age of the participants was 67 years (range: 56-80 years) and 60% were male. The most advanced finding at screening colposcopy was advanced adenoma in five and non-advanced adenoma in eight cases. Hyperplastic polyps were found in two participants and five participants were without any findings. At 5 °C storage temperature, almost all FITs showed fairly stable results throughout the 7-day observation period. At 20 °C, most FITs still showed fairly stable results over 4 days, whereas positivity rates significantly declined from day 4 on for most FITs at 35 °C. Major differences regarding the sample stability between FITs were observed.

Conclusion

FIT-specific Hb decay according to ambient temperature and time period between sampling and test evaluation requires careful consideration in the design of FIT-based screening programs.

SUBMITTER: Gies A

PROVIDER: S-EPMC6033915 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND & AIMS:Biomarker assays could increase the accuracy of noninvasive detection of colorectal cancer (CRC); fecal immunochemical tests (FITs) are estimated to miss 27%-47% of CRCs and 70%-80% of advanced adenomas per round of screening. We investigated the conditions under which biomarker screens would be cost-effective compared with FIT screens of average-risk individuals. METHODS:We used the MISCAN-Colon microsimulation model to estimate the effects of various CRC screening test characteristics on life-years gained (LYG) and; age-specific all-cause mortality was based on the 2010 Dutch life tables. Simulated CRC incidence rate and CRC stage distribution were calibrated to observed data in The Netherlands from 1999 through 2003 (before opportunities for screening). Survival rates after diagnosis of CRC at an age younger than 75 years were based on CRC relative survival data from 1985 through 2004; survival for individuals diagnosed at an age of 75 years or older was adjusted to fit the observed age-increasing mortality/incidence ratio. We modeled FIT along with hypothetical biomarker tests with different test performance levels. For each biomarker test we calculated the maximum unit cost for the test to be cost-effective compared with FIT, assuming a willingness-to-pay threshold of €50,000 ($56,000) per LYG. RESULTS:Biennial FIT screening of subjects 55-75 years old provided 84.9 LYG at a cost of €122,000 ($137,000) per 1000 participants. Considering a unit cost of €7 ($8) for FIT (including kit and analysis only, excluding organizational costs), a biomarker test that detects CRC with higher levels of specificity and sensitivity (100%) and advanced adenomas at a proportionally higher level of sensitivity (53%) should never exceed a cost of €51 ($57). The threshold cost could increase to more than €200 ($224) for high-performing biomarker tests in cases of limited colonoscopy capacity or higher uptake of this test. CONCLUSIONS:By using the MISCAN-Colon microsimulation model to estimate effects of CRC screening tests, we found that for a biomarker test with increased overall performance to be cost-effective, it should not exceed 7-fold the unit cost of FIT. This maximum would increase substantially if colonoscopy becomes more expensive or scarce, or if the new test has higher screening uptake. These values could be used to estimate the added value of new biomarkers compared with current FIT screening.

Project description:BackgroundPerformance characteristics of fecal immunochemical tests (FITs) to screen for colorectal cancer (CRC) have been inconsistent.PurposeTo synthesize data about the diagnostic accuracy of FITs for CRC and identify factors affecting its performance characteristics.Data sourcesOnline databases, including MEDLINE and EMBASE, and bibliographies of included studies from 1996 to 2013.Study selectionAll studies evaluating the diagnostic accuracy of FITs for CRC in asymptomatic, average-risk adults.Data extractionTwo reviewers independently extracted data and critiqued study quality.Data synthesisNineteen 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.LimitationsOnly English-language articles were included. Lack of data prevented complete subgroup analyses by FIT brand.ConclusionFecal 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 sourceNational Institute of Diabetes and Digestive and Kidney Diseases and National Cancer Institute.