[Establishing the Blood Donor Deferral Criterion in TP ELISA Test]

Area of Science:

• Immunology
• Public Health
• Clinical Diagnostics

Background:

• Blood donation screening is crucial for preventing transfusion-transmitted infections.
• Accurate identification of false positives in syphilis screening is essential for maintaining an adequate blood supply.
• Current methods may lead to the exclusion of eligible blood donors due to borderline serological results.

Purpose of the Study:

• To establish a reliable shielding threshold value for Treponema pallidum (TP) antibody Enzyme-Linked Immunosorbent Assay (ELISA) in unpaid blood donors.
• To minimize the exclusion of true positive blood donors from future donations.
• To optimize the management of blood donors identified as reactive for TP antibodies.

Main Methods:

• Serological status of 517 anti-TP ELISA reactive samples was confirmed using Treponema pallidum particle agglutination (TPPA).
• Shielding thresholds were determined using Receiver Operating Characteristic (ROC) curve analysis for 99% specificity and percentile methods for 95% positive predictive value.
• Applicability of initial thresholds was validated on 283 routinely tested reactive specimens.

Main Results:

• The 99% specificity threshold for reagent A was 13.33-16.18, and for reagent B was 13.17-19.85.
• The 95% positive predictive value threshold for reagent B was 6.62.
• Shielding thresholds based on 99% specificity achieved 100% true positive rates, while 95% positive predictive value thresholds achieved 98.4%-99% true positive rates.
• Recommended shielding limits were 13.33 for reagent A and 13.17 for reagent B.

Conclusions:

• The established TP antibody ELISA shielding threshold effectively reduces the number of blood donors incorrectly excluded from donation.
• This optimized screening strategy enhances blood supply safety and donor retention.
• Implementation of these thresholds can improve the efficiency of blood donor management programs.