Establishing the Blood Donor Deferral Criterion in TP ELISA Test / 中国实验血液学杂志

OBJECTIVE@#To Establish the shielding threshold value of TP antibody ELISA for unpaid blood donors, so as to shield true positive blood donors from returning to team management.@*METHODS@#The real serological status of 517 samples with anti-TP ELISA reactivity was determined by confirmation test of Treponema pallidum particle agglutination (TPPA). The shielding threshold of TP antibody was preliminarily determined by using 99% specificity of ROC and 95% positive predictive value of percentile method, respectively. 283 TP antibody reactivity specimens routinely tested in our laboratory were selected to determine the applicability of the initial shielding values obtained by the two methods, and finally to determine the shielding threshold values of TP antibody donors.@*RESULTS@#The specific S/CO values of reagent A 99% were 13.33-16.18, that of reagent B 99% was 6.34, that of reagent B 99% was 13.17-19.85, and that of 95% was 6.62. Empirical evidence: 99% specific threshold shielding true positive rates of reagents A and B were 100%, 95% positive expected value shielding true positive rates were 98.4%, 99%. Final determination of 99% specific shielding threshold as a low value of blood donors shielding threshold. The shielding limits of reagent A and B were 13.33 and 13.17.@*CONCLUSION@#The shielding threshold of TP antibody ELISA for blood donors established in this study can help to reduce the number of blood donors returning to team management.

Evaluation of the Cutoff of Anti-HCV Antibody Enzyme-Linked Immunosorbent Assay in 7 Blood Station Laboratories / 中国实验血液学杂志

OBJECTIVE@#To evaluate the necessity and suitability of the anti-HCV ELISA teot gray zone setted up by 7 blood station laboratories.@*METHODS@#7 blood station laboratories were coded as 1, 2, 3, 4, 5, 6 and 7 respectively; 8 kinds of ELISA reagents were coded as A, B, C, D, E, F, G and H respectively. 1 or 2 of 8 ELISA reagents produced by different manufactories were used to detect the anti-HCV in specimens of same group by 7 blood station laboratories; the Westen blot was used to detect the specimens with difference of detected results so as to difine the serological status of specimens. The true positive rate of specimens detected by laboratories and gray zone-comfirined positive rate of specimens were accounted so as to analyze the necessity of setting up the gray zone for anti-HCV ELISA test of 7 blood station laboratories; the optimal cut-off value for anti-HCV ELISA test was determined in 7 blood station laborafories by ROC curve and the changes of sensitivity and specificity of 3 different cut-off value(laboratory work cut-off value, manifactory-recommended cun-off value and optimal cut-off value) were compared so as to analyze the suitability of gray zone for anti-HCV ELISA test in 7 blood station laboratories.@*RESULTS@#The true positive rate detected by 7 blood station laboratories, out of which coded 1 laboratory used 2 kinds of coded A, B reagents was 95.40%(1A), 99.23% (1B), 94.25% (2C), 96.17% (3D), 98.08% (4E), 96.93% (5F), 97.32%(6G) and 93.10%(7H). Except for 2C(94.25%) and 7H(93.10%), the true positive rate detected by laboratoies which not sutted up gray zone, the gray zone-con-firmed positive rate in 6 blood station laboratories setted up gray zone: was 0.00%, 0.00%, 21.43%, 0.00%, 0.00%, 0.00% and 38.89%. The comparison of 3 different cut-off valuces by ROC curve showed that the anti-HCV cut-off values in 5 laboratories(1B, 2C, 4E, 5F and 6G) were as follows: optimal cut-off value＞manufactory recommeded cut-off value＞laboratory work cut-off value, thus use of manufactory-recommeded cut-off value abreadly has reached the high sensitivity requinements for laboratory screening; however, the optimal cut-off value in laboratories 1A, 3B and 7H, thas the appropriate gray zone should be used. In 6 laboratories setting up gray zone, the gensitivity in 3D, 7H laboratories only a little improved (1.60% and 2.70% raspectively) in Eamparison between laboratory work cut-off value and manufactorg-recommeded cut-off value; moreover, the sensitivity in other laboratories not is changed, but the specificity decreased (0.20%-0.50%).@*CONCLUSION@#In addition to setting up the appropriate gray zone in laboratories 1A, 3D and 5H, the gray zone in other laboratories may be cancelled. Even in the same laboratory, the setting up the gray zone also should be scientifically assessed, the same scale cannot be blindly used, thus appropniate strategies should be established.