TY - JOUR
T1 - Utility of a panel of sera for the alignment of test results in the worldwide multicenter study on reference values
AU - Ichihara, Kiyoshi
AU - Ozarda, Yesim
AU - Klee, George
AU - Straseski, Joely
AU - Baumann, Nikola
AU - Ishikura, Kiyohide
N1 - Funding Information:
Acknowledgments: The research funds used included a Scientific Research Fund (No. 21406015: 2009 –2011) provided by the Japan Society for the Promotion of Science (JSPS), which was used for the preparation of the panel of sera, purchase of CRMs, and logistics; the reagents required for testing all the target analytes in Uludag University were provided by Abbott Co. and those for testing in Japan were provided by Beckman Coulter Japan; the reagents used by the Mayo Clinic and ARUP Laboratories were procured with institutional research funds; some of the immunoturbidometric reagents for the study in Japan were provided by Nittobo Co. We are very grateful to the members of the Scientific Division of the IFCC, especially Prof. Philippe Gillery, for critical review and editing of this manuscript.
PY - 2013/5
Y1 - 2013/5
N2 - Background: In a planned International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) worldwide study on reference intervals (RIs), a common panel of serum samples is to be measured by laboratories from different countries, and test results are to be compared through conversion using linear regression analysis. This report presents a validation study that was conducted in collaboration with four laboratories. Methods: A panel composed of 80 sera was prepared from healthy individuals, and 45 commonly tested analytes (general chemistry, tumor markers, and hormones) were measured on two occasions 1 week apart in each laboratory. Reduced major-axis linear regression was used to convert reference limits ( LL and UL ). Precision was expressed as a ratio of the standard error of converted LL or UL to the standard deviation (SD) comprising RI (approx. 1/4 of the RI width corresponding to between-individual SD). The allowable and optimal levels of error for the SD ratio (SDR) were set as . 0.250 and . 0.125, respectively, in analogy to the common method of setting limits for analytical bias based on between-individual SD. Results: The values for the calculated SDRs depended upon the distribution patterns of test results: skewness toward higher values makes SDR LL lower and SDR UL higher. However, the CV of the regression line slope, CV( b ), is less affected by skewness. The average of SDR LL and SDR UL (aveSDR) correlates closely with CV( b ) (r = 0.995). The aveSDRs of . 0.25 and . 0.125 corresponds approximately to CV( b ) values of . 11% and . 5.5%, respectively. For all results (i.e., n = 80), conversion was allowable (optimal) in 98% (89%) of the analytes, as judged by CV( b ). Resampling studies using random subsets of data with a data size (n) of 70 to 20 revealed that SDRs and CV( b ) gradually increase with reduction of n, especially with n . 30. Conclusions: CV( b ) is a robust estimator for judging the convertibility of reference values among laboratories, even with a skewed distribution. Assuming 40 sera to be a practical size for the panel, reference values of 89% (80%) of analytes examined were made comparable by regression analysis with the allowable (optimal) level of precision.
AB - Background: In a planned International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) worldwide study on reference intervals (RIs), a common panel of serum samples is to be measured by laboratories from different countries, and test results are to be compared through conversion using linear regression analysis. This report presents a validation study that was conducted in collaboration with four laboratories. Methods: A panel composed of 80 sera was prepared from healthy individuals, and 45 commonly tested analytes (general chemistry, tumor markers, and hormones) were measured on two occasions 1 week apart in each laboratory. Reduced major-axis linear regression was used to convert reference limits ( LL and UL ). Precision was expressed as a ratio of the standard error of converted LL or UL to the standard deviation (SD) comprising RI (approx. 1/4 of the RI width corresponding to between-individual SD). The allowable and optimal levels of error for the SD ratio (SDR) were set as . 0.250 and . 0.125, respectively, in analogy to the common method of setting limits for analytical bias based on between-individual SD. Results: The values for the calculated SDRs depended upon the distribution patterns of test results: skewness toward higher values makes SDR LL lower and SDR UL higher. However, the CV of the regression line slope, CV( b ), is less affected by skewness. The average of SDR LL and SDR UL (aveSDR) correlates closely with CV( b ) (r = 0.995). The aveSDRs of . 0.25 and . 0.125 corresponds approximately to CV( b ) values of . 11% and . 5.5%, respectively. For all results (i.e., n = 80), conversion was allowable (optimal) in 98% (89%) of the analytes, as judged by CV( b ). Resampling studies using random subsets of data with a data size (n) of 70 to 20 revealed that SDRs and CV( b ) gradually increase with reduction of n, especially with n . 30. Conclusions: CV( b ) is a robust estimator for judging the convertibility of reference values among laboratories, even with a skewed distribution. Assuming 40 sera to be a practical size for the panel, reference values of 89% (80%) of analytes examined were made comparable by regression analysis with the allowable (optimal) level of precision.
KW - Method comparison
KW - Multicenter study
KW - Panel of sera
KW - Reduced major-axis regression
KW - Reference interval
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U2 - 10.1515/cclm-2013-0248
DO - 10.1515/cclm-2013-0248
M3 - Article
C2 - 23633468
AN - SCOPUS:84882239789
SN - 1434-6621
VL - 51
SP - 1007
EP - 1025
JO - Clinical Chemistry and Laboratory Medicine
JF - Clinical Chemistry and Laboratory Medicine
IS - 5
ER -