The Application of the EP9-A Protocol in the Analysis of the Performance of the Immunofluorescence Assay for HCG Detection

Abstract

Objective The present study aims to evaluate the comparability of the results of two methodologies for detecting human chorionic gonadotropin (HCG) to assess whether the immunofluorescence method for detecting HCG is adequate for clinical applications. Methods Referring to the protocol requirements of the American Clinical Laboratory Standards Institute (CLSI) EP9-A2 (methodological matching and bias assessment with patient samples), we collected 40 fresh serum specimens from our outpatients and inpatients, including 20 specimens with abnormal HCG concentrations (eight samples with different concentration ranges were selected daily and HCG was measured simultaneously with the two testing systems for five consecutive days). The assays were performed on a Dxl 800 fully automated immunoassay analyzer from Beckman Coulter Inc., USA, as a comparative method and on a Jet-iStar 3000 immunoassay analyzer from Zhonghan Shengtai Inc. as an experimental method. Methodological comparison and bias assessment of the results of the two methods for HCG detection were performed. The OLR regression model was used for calculating bias and regression analysis, and Spearman’s rank correlation coefficient was used for correlation analysis. The correlation and comparability of the two systems were calculated based on the results of the analysis. Results A good correlation in HCG results in the range of 5–50,000 U/mL was obtained from the two assay systems (r = 0.998) with the regression equation of y = 1.020x + 12.96. The estimated deviation was within the permissible deviation and acceptable. Conclusion The results of HCG measurement by the two different assay systems were well correlated and comparable.