Performance evaluation of quantitative hemoglobin A and fetal hemoglobin testing using commercially lyophilized vs. in-house whole blood controls in Chinese clinical laboratories: a 12-year analysis of National External Quality Assessment Data.

OBJECTIVES

To analyze the performance of laboratories in the China National External Quality Assessment Scheme (China NEQAS) for HbA and HbF testing, and to propose strategies for quality improvement.

METHODS

Data were obtained from China NEQAS from 2013 to 2024 using both commercially lyophilized controls and in-house whole blood controls. The distributions of methods and instruments were analyzed. Inter-laboratory coefficient variations (CVs) and target values were compared between two types of controls and between method-instrument platforms over 12 years.

RESULTS

The in-house controls remained homogeneous and stable for almost one month at 2-8 °C and for one year at -80 °C. Capillary electrophoresis (CE) became the dominant method, adopted by 84.3 % of labs in 2024. For HbA, two EQA controls had comparable concentration ranges and inter-laboratory CVs. HbF in-house controls covered broader pathological concentrations than commercial ones. CE demonstrated lower inter-laboratory CVs for both analytes: HbA was 2.1 ± 1.8 % vs. 5.5 ± 4.8 % (high-performance liquid chromatography, HPLC) and 6.5 ± 4.1 % (agarose gel electrophoresis, AGE), while HbF was 3.2 ± 1.9 % vs. 5.0 ± 1.6 % (HPLC) and 8.6 ± 6.8 % (AGE). Significant discrepancies in maximum-to-minimum mean concentrations were observed among different method-instrument platforms when testing the same controls (up to 10 % for HbF).

CONCLUSIONS

In-house controls demonstrate homogeneity, stability and intrinsic commutability, and have an expanded concentration range, can serve as a reliable alternative to commercial controls for EQA. High-precision techniques such as CE should be favoured. Furthermore, the development of reference methods and commutable reference materials is essential for standardization.