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[External evaluation of serology results in blood banks in Colombia]
Mauricio Beltrán Durán1, Maribel Ayala Guzmán
1Instituto Nacional de Salud, Bogotá, Colombia. mbeltrand@hemagogus.ins.gov.co
Insights
A Colombian external quality program found 3% false negative results in blood screening, highlighting a need to improve testing quality for transfusion-transmitted infections like syphilis and hepatitis B. This impacts blood transfusion safety.
Area of Science:
- Transfusion Medicine
- Infectious Disease Screening
- Clinical Laboratory Science
Background:
- Blood banks in Colombia participate in an external quality program (EQP) to ensure the quality of screening for transfusion-transmitted infectious diseases.
- Accurate screening is crucial for preventing the transmission of infections through blood transfusions.
Purpose of the Study:
- To analyze serological results from Colombian blood banks within the National Institute of Health's EQP.
- To identify areas for improvement in blood screening quality for key infectious disease markers.
Main Methods:
- Blood banks tested panels of sera for hepatitis B surface antigen (HBsAg), antibodies to HIV 1-2, Trypanosoma cruzi, Treponema pallidum, hepatitis B core (HBc) antigen, hepatitis C virus (HCV), and human T-lymphotropic virus (HTLV).
- Common screening techniques included enzyme-linked immunosorbent assay (ELISA), microparticle enzyme immunoassay (MEIA), and hemagglutination.
- Results were submitted to the National Blood Banks Unit for analysis.
Main Results:
- Out of 46 participating blood banks, 43 (93%) submitted results.
- Enzyme-linked immunosorbent assay (ELISA) was the most frequently used method (83%).
- A total of 49 (5%) false positive and 12 (3%) false negative results were reported. False negatives were most common for syphilis (6) and Chagas' disease (2).
- Higher rates of discordant results were observed in blood banks processing fewer than 6,000 units annually.
Conclusions:
- The 3% false negative rate in blood screening is considered high, as negative results are not typically retested before transfusion.
- There is a critical need to review and enhance blood screening procedures in Colombia.
- Particular attention should be given to improving performance at centers that demonstrated lower quality during the EQP exercise.
Objective:
To analyze the serological results found in Colombian blood banks that participate in the external quality program (EQP) of that country's National Institute of Health, in order to improve the quality of the screening of blood for the main serological markers of transfusion-transmitted infectious diseases.
Methods:
Each blood bank received a panel of six sera with different reactivity and positivity to hepatitis B surface antigen (HBsAg), as well as to antibodies to HIV 1-2, Trypanosoma cruzi (the causative agent of Chagas' disease), Treponema pallidum (the causative agent of syphilis), hepatitis B core (HBc) antigen, hepatitis C virus (HCV), and human T-lymphotropic virus (HTLV). The screening techniques used were enzyme-linked immunosorbent assay (ELISA), microparticle enzyme immunoassay (MEIA), and hemagglutination. With the panel sera, the participating blood banks were asked to apply the same tests that they use on a daily basis to screen blood units and to send their results to the National Blood Banks Unit of the Colombian National Institute of Health.
Results:
Of the 46 blood banks participating in the EQP, 43 of them (93%) returned their results within the requested timeframe. The ELISA test was the one that was used most often (83.0%). There were a total of 49 (5%) false positive results and 12 (3%) false negative results. Of those 12 false negative results, 6 of them corresponded to the detection of syphilis, 2 to Chagas' disease, 2 to anti-HBc antibodies, 1 to anti-HCV antibodies, and 1 to HBsAg. Eighty percent of the discordant results came from 23 blood banks that each collected fewer than 6 000 units of blood per year, and 15% came from 5 blood banks that collected 6 000 to 12 000 units per year. One of the blood banks that collected more than 12 000 units annually had three false positive results, and none of those larger blood banks had any false positive results.
Conclusions:
The percentage of false negative results (3%) found during the EQP can be considered high, since tests that are negative during blood screening are not repeated, and the decision to declare a unit of blood suitable for transfusion is based on that single result. There is a need to thoroughly review the procedures for screening blood in Colombia, particularly at the centers that performed poorly in this EQP exercise.
