National external quality assessment scheme for lymphocyte immunophenotyping in Belgium

Area of Science:

• Clinical Immunology
• Laboratory Medicine

Background:

• A voluntary external quality assessment (EQA) scheme for lymphocyte immunophenotyping was established in Belgium in 2000.
• This initiative aimed to standardize and improve the quality of flow cytometry analysis in clinical laboratories.

Purpose of the Study:

• To analyze the performance and trends of the Belgian EQA scheme for lymphocyte immunophenotyping over its first six surveys.
• To evaluate interlaboratory and intralaboratory variability in cell counting and phenotyping.

Main Methods:

• Analysis of fresh EDTA-anticoagulated whole blood specimens distributed to 41 participating laboratories.
• Participants reported white blood cell counts, lymphocyte percentages, and percentages/absolute numbers of CD3+, CD4+, CD8+, and CD19+ cells.
• Methodology surveys assessed laboratory practices and data reporting.

Main Results:

• Median intralaboratory coefficients of variation were low for cell percentages (1.0-3.2%).
• Interlaboratory variability was consistently below 6.5% for CD3+ and CD4+ percentages, and below 9.5% for CD8+ percentages.
• Median coefficients of variation for absolute cell counts were higher (10.1-16.5%).
• A decrease in laboratories measuring total CD4+ and CD8+ cells was observed, while between-laboratory variability remained stable.

Conclusions:

• The EQA scheme demonstrated effectiveness in maintaining stable interlaboratory performance over time.
• Individual laboratories showed significant improvements in their results, indicating the value of the assessment program.
• Standardization of lymphocyte immunophenotyping methods is crucial for reliable clinical diagnostics.