ABSTRACT
【Objective】 To investigate the applicability of Beckman PK7300 for TPPA testing on anti-TP reactive specimens from blood donors. 【Methods】 1) The TPPA test using Beckman PK7300 (abbreviated as instrument method) had been established and the performance was verificated by calculating the total compliance rate, positive compliance rate and negative compliance rate as compared with the manual method. The repeatability of this instrument method was also evaluated. 2) The applicability of the instrument method was evaluated by examing 555 TP-reactive samples for 6 consecutive days, so as to analyze the readable reading rate, agglutination strength distribution and other control methods. 【Results】 1) The total, positive, and negative compliance rates of TPPA detection by both instrumental and manual methods were 100% (kappa value =1). The SPC value of samples, read manually as " + + ", was less than or equal to 3 by Beckman PK7300; the SPC value of samples, read manually as " -", was greater than or equal to 20 by Beckman PK7300. The two methods were well consistent. The instrument method was repeated for 12 times for the same samples, and the accuracy rate was 100% (12 / 12), with good repeatability.2) The results of the TPPA test in 555 anti-TP reactivity specimens showed an overall readable rate of 99.82%(554/555). The SPC values of the negative and unsensitized particles of TPPA were distributed on both sides of the determination value without crossover. The control and monitor thoughout the test were carried out automatically by the instrument. 【Conclusion】 The TPPA test conducted by the Beckman PK7300 fully automatic blood group instrument is suitable for the confirmatory experiment of anti-TP reactive specimens in blood center laboratories, which could realize the automation and standardization of TPPA detection.
ABSTRACT
【Objective】 To explore the viability of classification management of HIV reactive blood donors based on test results in blood screening laboratory. 【Methods】 According to the HIV test results of blood donors (including twice ELISA and once NAT), the HIV reactive blood donors were divided into three groups. Group 1 was all-test reactive (both ELISA and NAT were reactive), group 2 serological reactive (only ELISA was reactive), and group 3 NAT reactive (only NAT was reactive). The HIV test results of 191 628 blood donors from May to December 2017 were analyzed. Samples with positive RIBA results and / or the repeated reactive NAT results were determined as HIV true positive. The yielding rates of HIV true positivity in each group were analyzed. Receiver operating characteristic curve (ROC curve) was used to elevate the S/CO limit under 99% specificity as the blood donor deferral limit for ELISA. 【Results】 A total of 180 HIV reactive samples were detected out of 191 628 blood donors, including 77 positive cases in group 1, 100 in group 2 and 3 in group 3. 1) The HIV reactive results were diverse. Among the 82 true positive blood donors, 4 were early HIV infection (3 HIV antibody+ antigen window period yield, 1 HIV antibody window period yield), 2 were suspected elite controllers, and 76 cases were both serology and NAT reactive. 2) The overall yielding rate of HIV was 47.67%, with group 1 (100%) = group 3 (100%) > group 2 (2.17%), showing statistically significant (P0.05). All true positive blood donors in group 1 and group 2 could be accurately screened by using the blood donor deferral limit for ELISA1 and ELISA2 simultaneously. 【Conclusion】 The composition of HIV results among blood donors is diverse and complex. It is necessary to continuously improve the awareness of HIV prevention and control. The classification of HIV reactive blood donors is conducive to conduct fine and scientific management. The blood donors in group 1 and group 3 should be permanently deferral, and the suspected HIV elite controllers in group 2 should be paid attention to and permanently deferral.
ABSTRACT
【Objective】 To discuss the reliability and applicability of the current blood deferral strategy concerning anti-TPreactive blood donors (by ELISA). 【Methods】 TPPA confirmatory test was performed on the samples routinely detected by two different anti-TP ELISA reagents(reagent 1 and reagent 2), and the test data of dual reagent reactive and one reagent reactive blood donors were analyzed to determine the possibility of true positivity. 【Results】 1 624 anti-TP reactive samples(by ELISA) were collected, among which 1 467 were dual reagent reactive, 77 were reagent 1 reactive, and 80 were reagent 2 reactive. TPPA results showed that the positive predictive value (PPV) of dual reactive samples was 85.48%. Samples with high S/CO value (reagent 1≥13 and/or reagent 2 >17) were more likely to be true positive, with the PPV at 98.56% (reagent 1) and 99.13% (reagent 2), respectively, which were significantly higher than that when the S/CO value was≥1. Among the samples reactive to one reagent, 2 were confirmed positive in reagent 1 and 3 in reagent 2, with the PPV at 2.60% and 3.75% respectively, and had no correlation with high S/CO value. 【Conclusion】 Dual-reagent reactive donors with high S/CO value showed high possibility of true positivity, therefore should be deferred. TPPA test is helpful to identify true positivity in one-reagent reactive donors. Confirmatory test and follow-up should be a supplement to the current blood donor deferral strategy to ensure blood safety.
ABSTRACT
【Objective】 To assess the status of HCV infection by analyzing the results of anti-HCV reactive blood samples detected by the current blood testing strategy, and discuss the viability of classified management of reactive blood donors. 【Methods】 The anti-HCV reactive samples (dual ELISA and once NAT), from May 2017 to October 2018, were divided into three groups: samples both anti-HCV and HCV RNA reactive, sole HCV RNA reactive, and sole anti-HCV reactive, and all of them were confirmed by recombinant immunoblot assay (RIBA). The positive predictive value (PPV) between groups were compared. The sensitivity, specificity and PPV for each reagent under different screening threshold (screening threshold for routine detection, optimal screening threshold, and corresponding screening threshold of the highest PPV) were analyzed. The group with low PPV were stratified by ELISA S/CO values, and PPV by different screening threshold was compared. 【Results】 There were 939 reactive samples (0.49%, 937/191 627). Confirmed by RIBA, the positive rate of anti-HCV reactive samples was 10.67%(100/937). Two samples were sole HCV RNA reactive (0.001%). Both anti-HCV+ HCV RNA reactive samples were 6.71%(63/939), with the PPV of 96.83%(61/63). Sole anti-HCV reactive samples were 93.08(874/939), with the PPV of 4.46%(39/874), among which PPV by dual and one ELISA reagent were 18.72% and 0.15%, respectively, showing statistically significant difference (P<0.05). The PPV between different S/CO values was statistically significant (P<0.05). The optimal screening thresholds of anti-HCV reagent were 9.29 and 3.97, according to the ROC curve, with significant difference noticed in PPV by different screening threshold (P<0.05). PPV in the sole anti-HCV reactive group increased from 4.46% (the routine screening threshold) to 49.35%(the optimal screening threshold), and the difference was statistically significant (P<0.05). 【Conclusion】 The blood donors with both anti-HCV and HCV RNA reactive can be determined as HCV infection and need to be permanently deferred. The S/CO value of sole anti-HCV reactive samples was positively correlated with RIBA confirmation results, and the higher the S/CO value, the greater the chances of positive confirmation are. With the current blood screening strategy, the HCV infection status of sole anti-HCV reactive blood donors can be determined by establishing a screening threshold with high PPV or adding confirmatory test.