Allowable total error in CD34 cell analysis by flow cytometry based on state of the art using Spanish EQAS data

Area of Science:

• Clinical Laboratory Science
• Hematopoietic Stem Cell Transplantation
• Flow Cytometry

Background:

• Accurate CD34+ hematopoietic stem cell (HSC) enumeration is critical for HSC transplantation success.
• Variability in CD34+ cell counts arises from biological, assay, and technological factors.
• External Quality Assurance Schemes (EQAS) aim to minimize inter-laboratory variations in cell enumeration.

Purpose of the Study:

• To estimate total error (TE) values for CD34 cell enumeration using state-of-the-art (SOTA) methods and EQAS data.
• To define quality specifications by comparing TE across different CD34 cell count levels and time periods.
• To assess the impact of technical advancements on CD34 cell enumeration accuracy.

Main Methods:

• Analysis of 3,994 results from 40 laboratories over 11 years (2011-2022) from the IC-2 Stem Cells Scheme.
• Data divided into two periods: 2011-2016 and 2017-2022 for comparative analysis.
• Calculation of TE values achieved by at least 60-90% of laboratories at different CD34 cell count ranges (<15, 15-25, >25 cells/μL).

Main Results:

• A decrease in SOTA-based TE for CD34 cell enumeration was observed in the 2017-2022 period compared to 2011-2016.
• A significant increase in P75 TE values was found in the low CD34 range (<15 cells/μL) (p<0.001).
• TE is measure-dependent and responsive to precision enhancement strategies.

Conclusions:

• Technical advancements have contributed to a reduction in TE for CD34 cell enumeration over time.
• EQAS-measured TE can serve as a quality specification for implementing ISO 15189 standards in clinical laboratories.
• Improved precision in CD34 cell enumeration enhances the reliability of clinical decisions in HSC transplantation.