Comparison of performance of two Treponema pallidum automated chemiluminescent immunoassays in blood donors

Diagnostic Efficacy of Photostimulated Chemiluminescence Assay for Detecting Anti-HIV Antibodies: A Retrospective Study

The transmission of human immunodeficiency virus (HIV) through blood poses a slightly increased risk. As a result, patients requiring blood transfusions should be screened for HIV antibodies. This study examined the diagnostic effectiveness of the photostimulated chemiluminescence assay in detecting anti-HIV antibodies and determined the cut-off value for this method. The performance of the fully automated photostimulated chemiluminescence assay system was validated according to CNAS-GL038:2019 (2020) and CNAS-GL037:2019 (2019) guidelines. A retrospective study was conducted at the Department of Medical Laboratory, Nanjing Tongren Hospital, affiliated with Southeast University, from January 2020 to December 2022. A total of 77,386 cases were tested for anti-HIV antibodies using the photostimulated chemiluminescence assay, with 79 cases initially testing positive. The method's performance in detecting anti-HIV antibodies was evaluated using the Receiver Operating Characteristic (ROC) curve and the average Coefficient of Variation (CV) value of 3-year in-house quality control. The precision, detection limit, coincidence rate, and critical value of the performance verification results met the requirements. Using Western blotting (WB) as the reference method, positive cases were initially screened using the light-induced chemiluminescence method to determine the cut-off index (COI) value and draw the ROC curve. The maximum area under the ROC curve using the chemiluminescence method was 0.997, with a cutoff value of < 28.56, sensitivity of 98%, specificity of 100%, Jordan index of 0.98, and an average CV value of 3.55%. In conclusion, the photostimulated chemiluminescence assay has good diagnostic efficacy in detecting anti-HIV antibodies and is suitable for rapid screening before blood transfusion and surgery.

Evaluation of ELISA and CLIA for Treponema pallidum specific antibody detection in China: A multicenter study

BACKGROUND

Considering the rapid increase of syphilis infections in several countries including China, searching for a screening test with sufficient sensitivity and specificity is extremely urgent. The current study mainly researched the performance for Treponema pallidum (TP) detection by electro-chemiluminescence immunoassays (ECLIA), chemiluminescence immunoassays (CLIA) and four commercially available ELISA assays commonly used in China.

METHODS

1372 plasma samples collected from blood centers/banks were tested with 6 assays in 8 laboratories with the Western blot (WB) or TP particle agglutination assay (TPPA) as confirmatory tests.

RESULTS

With the WB or TPPA as confirmatory test, the ECLIA demonstrated the highest specificity (95.2%) and Kappa coefficient (0.915), but lowest sensitivity (97.2%) compared with the other 5 assays. While the Wantai-ELISA showed the highest sensitivity (99.6%) among the 6 assays. Sensitivities were found to be significantly increased when any two of the six assays were combined for TP detection. Our study demonstrated that the Wantai-ELISA combined with the ECLIA or the KHB-ELISA or the InTec-ELISA would increase the sensitivities up to 100%. Further analysis showed that the specificities and positive predictive values were both 100.0% when cut-off of S/CO values were served as 15.42 for the ECLIA and 7.14 for the CLIA, indicating that samples under these conditions can be directly considered as positive without confirmation.

CONCLUSIONS

The CLIA and the ECLIA are more specific than ELISA to detect TP antibodies. However, ELISA is a sensitive method, especially in combination with the CLIA or the ECLIA or another types of ELISA, suitable for the routine screening of blood donations in China.

Evaluate performance of the Abbott chemiluminescent microparticle immunoassay assay for detection of syphilis infection in Chinese blood donors

Background and Objectives

To prevent Treponema Pallidum (TP) transmission from blood transfusion, enzyme‐linked immunosorbent assay (EIA) for anti‐TP has been widely used in routine blood donation screening in China for many years. The aim of this study was to evaluate the performance of the Abbott CMIA assay for detection of anti‐TP in Chinese blood donors.

Materials and methods

A total of 2420 plasma samples, already routinely screened for anti‐TP by two different EIAs, from four blood Centers were tested for anti‐TP by Abbott CMIA. Subsequently, all samples with positive results by one or both EIAs and/or by Abbott CMIA were subjected to confirmatory testing (CT) using recombinant immunoblot assay (RIBA) or Treponema Pallidum particle agglutination assay (TPPA). TP infection was defined by a RIBA or TPPA positive.

Results

Compared with two EIAs strategy, Abbott CMIA showed a relatively best sensitivity as 98.80% (95% CI: 97.44%‐100.16%) and a relatively best specificity as 99.58% (95% CI: 99.30%‐99.85%), yielding the best consistency (99.49%) between anti‐TP CT results with the highest κ value of .98.

Conclusion

This is the first study to evaluate the performance of the Abbott CMIA assays for detection of syphilis in Chinese blood donors. Our results suggested that CMIA performed better than both EIAs, and implementation of CMIA replacing two different EIA reagents might help to further reduce the risk of transfusion‐transmitted TP infection, decrease unnecessary blood waste and loss of blood donors.

Evaluation of three automated Treponema pallidum antibody assays for syphilis screening

The accuracy of the test is critical for the syphilis serology diagnosis. This study aims to evaluate the values of the Elecsys syphilis assay, the Architect syphilis assay, and the Mindray syphilis assay, as syphilis screening tests for pregnant women and patients with syphilis or other diseases. A reverse algorithm was used for the syphilis serology diagnosis. Serum samples (n = 584) were tested with three automated screening assays. All reactive sera by one, two, or three screening assays were further analyzed with the tolulized red unheated serum test (TRUST). Inconsistent results were confirmed by the Treponema pallidum particle agglutination assay (TPPA). The final patient diagnosis was made according to the results of syphilis serology, clinical evidence, and past medical history. The sensitivity, specificity, accuracy, and kappa value of each assay were as follows: for the Elecsys syphilis assay, 100.0%, 98.5%, 98.6%, and 0.927, respectively; for the Architect syphilis assay: 100.0%, 94.5%, 95.0%, and 0.770; and for the Mindray syphilis assay: 100.0%, 97.0%, 97.3%, and 0.862. The McNemar test showed that there were significant differences in the performance between the Elecsys syphilis assay and the Architect syphilis assay (P < 0.001), and between the Mindray syphilis assay and the Architect syphilis assay (P = 0.001). Our study demonstrated that three automated Treponema pallidum antibody assays generally showed high sensitivities and specificities, and so, they are suitable for use in screening for syphilis. The performances of the Elecsys syphilis assay and the Mindray syphilis assay are superior to Architect syphilis assay.

Occult Hepatitis Infection in Transfusion Medicine: Screening Policy and Assessment of Current Use of Anti-HBc Testing

HBV still represents a global risk factor in transfusion medicine. The residual risk of HBV is not limited to pre-seroconversion window period but it extends to donors with occult HBV infection (OBI) characterized by the presence of HBV DNA in liver and by the absence of the virus surface antigen. Each country developed an appropriate blood screening policy according to local HBV prevalence, yields of infectious units per different screening methods and cost-effectiveness. We underline the need of maintaining a high level of attention for OBI carrier identification in all blood banks worldwide where the screening procedures are generally based on a combination of both serological markers and nucleic acid amplification test. In this context, markers such as hepatitis B surface antibodies and hepatitis B core antibodies (anti-HBc) might be useful, although the use of this latter is highly debated and still controversial. Our aim is to give an overview on the relevant diagnostic approaches for the routine screening for HBV focusing on the feasibility of anti-HBc testing as precautionary measure in preventing OBI transmission worldwide. In our tailored algorithm, the loss of about 1% of 'anti-HBc only' donors, does not significantly affect the blood supply while improving recipient safety.