Performance verification of laboratory-developed clinical chemistry system-Analytical measurement range and clinical reportable range / 中华检验医学杂志

ABSTRACT

Objective To estimate the methodology for evaluating the analytical measurement range ( AMR) and the clinically reportable range ( CRR) in lab-developed system in clinical chemistry .Methods Method evaluation .Take serum CK for instance , a series of samples were prepared from both a specimen with a high concentration of the analyte of interest and a specimen with a low concentration for the following assays.Average slope method , linear dilution recovery method and the method recommended by Clinical and Laboratory Standards Institute ( CLSI ) EP6-A were used to established AMR in the lab-developed clinical chemistry system.Based on the maximum valid dilution of the specimen and the results of AMR , CRR were determined.One-half of the total error allowance ( TEa) of Chinese health standard was set up as allowance error (7.5%).Results X-Y scatter plot was made by assigning sample numbers to the horizontal axis and actual measured values to the vertical axis , which determined the upper limit of AMR was approximate 1 651 U/L.The results analyzed by average slope method indicated that the linear correlation between expected values and actual measured values was determined , the correlation (r), the intercept (a) and the slope (b) met the linear standard, and AMR was 5-1 699 U/L.The results analyzed by EP6-A indicated that the best fitting curve was obtained by using cubic polynomial method , and the linearity deviation of the minimum concentration was -77.1%, which exceeded one-half of TEa.Followed by the deletion of the maximum concentration , the resumed experiment was done .The results showed that the nonlinear coefficient c of quadratic polynomial and the nonlinear coefficient c and d of cubic polynomial have no significant difference to 0, and AMR was 7.5-1 458.0 U/L.By linear dilution recovery method , the linear correlation between expected values and actual measured values was determined , the correlation ( r) , the intercept ( a) and the slope ( b) met the linear standard , the recovery rates was between 100.0%and 104.8%, and AMR is 5 -1 699 U/L.The CRR was determined to be 5 -33 880 U/L, which met the standard of TEa . Conclusions Average slope method, linear dilution recovery method and EP 6-A method were all used to established AMR in lab-developed clinical chemistry system .Without complicated statistical analysis , linear dilution recovery method was suitable for clinical use .The linearity deviation of the minimum concentration analyzed by EP6-A did not meet the standard of the quality objective system , suggesting defects in the statistical analysis of the results .CRR was feasibly determined by using linear dilution recovery method align with AMR.