Accuracy of a fecal immunochemical test according to outside temperature and travel time

Clinical Epidemiology, Sep 2018

Accuracy of a fecal immunochemical test according to outside temperature and travel time Tobias Niedermaier,1,2 Korbinian Weigl,1–3 Anton Gies,2,4 Michael Hoffmeister,1 Hermann Brenner1,3,4 1Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), Heidelberg, Germany; 2Medical Faculty Heidelberg, University of Heidelberg, Heidelberg, Germany; 3German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany; 4Division of Preventive Oncology, German Cancer Research Center (DKFZ) and National Center for Tumor Diseases (NCT), Heidelberg, Germany Background: Fecal immunochemical tests (FITs) are widely used and recommended for colorectal cancer (CRC) screening. Fecal hemoglobin (Hb) may degrade with long transport durations and high ambient temperatures, potentially reducing sensitivity to detect CRC and its precursors. This study aimed at investigating the impact of temperatures and sample travel times on diagnostic performance of a quantitative FIT for detection of advanced neoplasms (AN, CRC, or advanced adenoma).Methods: Participants of screening colonoscopy in south-western Germany conducted a quantitative FIT prior to bowel preparation between February 2012 and June 2016. From available locations and dates of stool sampling and transport, maximum ambient temperatures were linked to 2,870 participants aged 50–79 years and sample return durations were recorded. The impact of ambient temperatures and return duration on FIT sensitivity and specificity was assessed for five different cutoffs between 10 and 25 µg Hb/g feces.Results: At a positivity threshold of 20 µg Hb/g feces, overall sensitivity and specificity for detecting any AN were 40% (95% CI, 35–47%) and 95% (95% CI, 94–96%), respectively. Inverse associations between maximum ambient temperature (median 18.1°C, inter-quartile range [IQR] =11.4–24.9°C) and sensitivity of FIT were observed which were stronger at higher cutoffs. Sample return durations (median 6 days, IQR =4–8 days) were not associated with variable sensitivities or specificities.Conclusion: Hb degredation during fecal sample transportation in summer months may be of some concern for diagnostic performance of the FIT evaluated under routine conditions in a middle-European climate. Keywords: advanced colorectal neoplasm, fecal immunochemical test, ambient temperature, sample travel time, sensitivity, hemoglobin degradation

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Accuracy of a fecal immunochemical test according to outside temperature and travel time

Authors Niedermaier T, Weigl K, Gies A, Hoffmeister M, Brenner H Received 4 April 2018 Accepted for publication 22 May 2018 Published 17 September 2018 Volume 2018:10 Pages 1203—1213 DOI https://doi.org/10.2147/CLEP.S170169 Checked for plagiarism Yes Review by Single-blind Peer reviewers approved by Dr Colin Mak Peer reviewer comments 2 Editor who approved publication: Professor Vera Ehrenstein Tobias Niedermaier,1,2 Korbinian Weigl,1–3 Anton Gies,2,4 Michael Hoffmeister,1 Hermann Brenner1,3,4 1Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), Heidelberg, Germany; 2Medical Faculty Heidelberg, University of Heidelberg, Heidelberg, Germany; 3German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany; 4Division of Preventive Oncology, German Cancer Research Center (DKFZ) and National Center for Tumor Diseases (NCT), Heidelberg, Germany Background: Fecal immunochemical tests (FITs) are widely used and recommended for colorectal cancer (CRC) screening. Fecal hemoglobin (Hb) may degrade with long transport durations and high ambient temperatures, potentially reducing sensitivity to detect CRC and its precursors. This study aimed at investigating the impact of temperatures and sample travel times on diagnostic performance of a quantitative FIT for detection of advanced neoplasms (AN, CRC, or advanced adenoma). Methods: Participants of screening colonoscopy in south-western Germany conducted a quantitative FIT prior to bowel preparation between February 2012 and June 2016. From available locations and dates of stool sampling and transport, maximum ambient temperatures were linked to 2,870 participants aged 50–79 years and sample return durations were recorded. The impact of ambient temperatures and return duration on FIT sensitivity and specificity was assessed for five different cutoffs between 10 and 25 µg Hb/g feces. Results: At a positivity threshold of 20 µg Hb/g feces, overall sensitivity and specificity for detecting any AN were 40% (95% CI, 35–47%) and 95% (95% CI, 94–96%), respectively. Inverse associations between maximum ambient temperature (median 18.1°C, inter-quartile range [IQR] =11.4–24.9°C) and sensitivity of FIT were observed which were stronger at higher cutoffs. Sample return durations (median 6 days, IQR =4–8 days) were not associated with variable sensitivities or specificities. Conclusion: Hb degredation during fecal sample transportation in summer months may be of some concern for diagnostic performance of the FIT evaluated under routine conditions in a middle-European climate. Keywords: advanced colorectal neoplasm, fecal immunochemical test, ambient temperature, sample travel time, sensitivity, hemoglobin degradation Plain language summary Fecal immunochemical tests (FITs) for colorectal cancer (CRC) screening are typically conducted at home and sent to a laboratory for analysis. By measuring human hemoglobin in stool, FITs detect a significant share of advanced neoplasms (CRC or advanced adenoma). However, hemoglobin is not stable when exposed to high temperatures for a longer time, potentially decreasing sensitivity of FIT. Previous studies indicated that positivity of FIT decreases with higher ambient temperatures. By contrast, associations between ambient temperatures and sensitivity and specificity of FIT, using colonoscopy as gold standard, have not yet been assessed. Thus, we assessed the associations between ambient temperature, sample return time, and sensitivity and specificity of a widely used fecal immunochemical test (FOB Gold) using various cutoffs for detecting advanced colorectal neoplasms in a large screening population in south-western Germany. Sensitivity and specificity at five different cutoffs were examined among 2,870 participants of screening colonoscopy who collected a fecal sample for FIT prior to large bowel preparation. Inverse associations between maximum ambient temperature and sensitivity of FIT were observed which were larger at higher cutoffs. Sample return durations were not associated with sensitivities or specificities. In conclusion, avoidance of summer days when using fecal immunochemical tests requiring laboratory analysis might help ensuring high sensitivity of the investigated FIT in a middle-European climate for detecting AN. Introduction Fecal immunochemical tests (FITs) are widely used and recommended for colorectal cancer (CRC) screening.1,2 They measure the hemoglobin (Hb) concentration in fecal samples that are typically sent to a laboratory for analysis. Although FITs were shown to clearly outperform traditional guaiac-based fecal occult blood tests in terms of diagnostic performance,3–5 potential Hb degradation, especially, during longer sample travel times and at higher ambient temperatures is of potential concern, as it may reduce sensitivity to detect CRC or its precursors. Sever (...truncated)


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Tobias Niedermaier, Korbinian Weigl, Anton Gies, Michael Hoffmeister, Hermann Brenner. Accuracy of a fecal immunochemical test according to outside temperature and travel time, Clinical Epidemiology, 2018, pp. 1203-1213, DOI: 10.2147/CLEP.S170169