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A Rapid and Chemical-free Hemoglobin Assay with Photothermal Angular Light Scattering
Published on: December 7, 2016
Recommendations for proficiency testing criteria for hemoglobin A1c based on the Shanghai Center for Clinical
Yi Ju1, Zhimin Tim Cao2,3, Qing Li1
1Shanghai Center for Clinical Laboratory, Shanghai, P.R. China.
Insights
Implementing a ±6% or ±7% acceptance limit for glycated hemoglobin A1c (HbA1c) proficiency testing ensures high laboratory performance. This range maintains analytical quality and clinical utility for HbA1c testing.
Area of Science:
- Clinical Chemistry
- Laboratory Medicine
- Diagnostic Testing
Background:
- The US Centers for Medicare & Medicaid Services proposed regulating glycated hemoglobin A1c (HbA1c) in 2019.
- Concerns were raised that a ±10% acceptance limit (AL) for proficiency testing (PT) might compromise analytical performance and clinical utility.
Purpose of the Study:
- To assess the impact of various acceptance limits (ALs) on HbA1c proficiency testing (PT) performance.
- To provide evidence for an appropriate AL for HbA1c testing regulation.
Main Methods:
- Ten patient EDTA-whole blood specimens were distributed in 2018 and 2019 PT events to 318-336 laboratories.
- HbA1c concentrations were measured using various methodologies; targets were set by secondary reference measurement procedures (SRM).
- Event Unsatisfactory Status was assigned for laboratories with ≥2 failed results (outside SRM-defined target ± AL) out of five samples.
Main Results:
- Overall Laboratory Event Unsatisfactory Rates varied with ALs: ±5% (11.3-12.2%), ±6% (4.8-5.3%), ±7% (0.9-3.1%), ±8% (0.6-2.2%), ±9% (0.6-1.4%), ±10% (0.6-1.4%).
- HbA1c target values ranged from 33.3 mmol/mol (5.2 NGSP%) to 102.2 mmol/mol (11.5 NGSP%).
Conclusions:
- An AL of ±6% or ±7% (NGSP unit) is appropriate for PT evaluation of HbA1c results.
- These limits would ensure satisfactory event scores for approximately 95% of participating laboratories.
Objectives:
The US Centers for Medicare & Medicaid Services proposed in 2019 that glycated hemoglobin A1c (HbA1c) be a CLIA'88 regulated analyte. People who commented expressed concerns that the proposed acceptance limit (AL, HbA1c in NGSP unit) ±10% for proficiency testing (PT) would be unable to maintain already improved analytical performance and guarantee the clinical utility of HbA1c testing. Assessing impact of various ALs on PT performance is needed to provide scientific evidence for adopting an appropriate AL.
Methods:
Ten patient EDTA-whole blood specimens were distributed to 318 and 336 laboratories in the 2018 and 2019 PT events organized by Shanghai Center for Clinical Laboratory (SCCL). HbA1c concentrations were measured by participants using various methodologies commonly used in the USA and China. Targets were determined using secondary reference measurement procedures (SRM) at SCCL. "Failed Results" were those outside the SRM-defined target ± AL (5% through 10%). Laboratories with Failed Results ≥2 out of five samples per PT event obtained Event Unsatisfactory Status.
Results:
HbA1c target values ranged 33.3 mmol/mol (5.2 NGSP%) -102.2 mmol/mol (11.5 NGSP%) for 2018 event, and 33.3 mmol/mol (5.2 NGSP%) -84.7 mmol/mol (9.9 NGSP%) for 2019 event. Overall Laboratory Event Unsatisfactory Rates were 11.3-12.2%, 4.8-5.3%, 0.9-3.1%, 0.6-2.2%, 0.6-1.4% and 0.6-1.4%, at AL of ±5, ±6, ±7, ±8, ±9 and ±10%, respectively.
Conclusions:
The AL (in NGSP unit) of ±6% or ±7% for PT evaluation of HbA1c results would be appropriate, with satisfactory event scores for about 95% of participant laboratories in a PT event.
