| Part? Evaluation of HbA1c measurements on four analyzers systems ObjectiveTo evaluate the analytical performances of routine HbAlc measurements on 4 analyers systems.MethodsThe analytical methods with the corresponding Capillarys 2 Flex Piercing (Capillarys 2FP), Tosoh HLC-723 G8 (Tosoh G8), Premier Hb9210, and Roche Cobas c501 (Roche c501) analyzers were used in HbAlc assays to evaluate their analytical performances of pricision, accuray, linearity, method comparison and analytical interferences.ResultsThe precision of the four HbAlc assays (within-run coefficient of variation (CV):0.32-1.90%, total CV:0.53-1.94%) were well within the recommendations. The relative bias against the International Federation of Clinical Chemistry targets was less than 3mmol/mol or 0.3% for all four systems tested, indicating a good accuracy of the methods. Pearson correlation coefficient of the four analyzers was greater than 0.99 over the clinical range of HbAlc values. The HbAlc values of 80 adults showed a great correlation and agreement between methods, and the concordances in the HbAlc concentration of 48mmol/mol (6.5%) demonstrated a great interchangeability between methods. No interference was noticed with any of the methods at concentrations of 445.50 umol/L bilirubin,10.21 mmol/L triglyceride,10.29 mmol/L cholesterol, 19.10/10.90 mmol/L triglyceride/cholesterol,277.78 mmol/L glucose,50 mg/mL vitamin C, or 33.30 mg/mL aspirin. However, elevated HbF levels could interfere with the HbAlc results obtained by the Capillarys 2FP (>10%), Tosoh G8 (>5%, uncorrected;>30%, corrected), Premier Hb9210 (>15%), and Roche c501 (>5%;>20%, recalculated) instruments.ConelusionThe four HbAlc methods commonly used by commercial analyzers showed a good reliability and comparability, although HbF may impede the result.Part? Effect of Thalassemia on HbA1c Measurement by Four Methods and Screening the Thalassemia during HbA1c analysis by Capillarys 2FPObjectiveTo evaluate the effect of thalassemia on HbAlc measurement by four methods and explore the value of Capillarys 2FP for screening the thalassemia during HbAlc analysisMethodsA total of 99 normal adults (normal control) and 99 thalassemia patients from non-diabetic subjects were selected, and the HbAlc analysis performed by four systems were compared. At the same time, a total of 10 samples were quantified by the IFCC reference method to assess the accuracy of the system results. The HbA2 values from Capillarys 2FP were collected, then Receiver operating characteristic curve (ROC) were performed to determine the HbA2 cut-off values for screening ? and ? thalassemia.ResultsCompared with the normal adults, HbAlc values of thalassaemia patients obtained using Premier Hb9210 and Roche c501 were significantly lower (P<0.01); while, the values on Tosoh G8 were significantly higher (P<0.01); no significant difference was found on Capillarys 2FP (8 HbH samples were unmeasurable) (P>0.05). For the 10 samples, the HbAlc values by Premier Hb9210, Roche c501 and Capillarys 2FP (4 HbH samples were unmeasurable) were consistent with the IFCC results (bias<0.5% or 5mmol/mol); on Tosoh G8, a significant positive bias above 5 mmol/mol or 0.5%was noticed in 7 patients (5 HbH and 2 ?-thalassemia trait patients). For screening samples with ?-thalassaemia and ?-thalassemia, the optimal HbA2 cut-off values were?2.2%(area under curve (AUC) 0.850, sensitivity 80.0% and specificity 74.75%) and >3%(AUC 1.0, sensitivity 100.0% and specificity 100.0%) on C2FP.ConelusionCompared with the normal adults, there were lower HbAlc values in thalassemia patients on Hb9210 and cobas c501. Thalassemia might interfere the measurement of HbAlc values on the ion-exchange HPLC method G8. HbA2 and abnormal chromatogram on C2FP could provide valuable information for thalassemia screening. |
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