Assessment of quality control producy for thalassemia screening using MCV and MCH approaches

Abstract

A combined MCV/DCIP or MCH/DCIP is one of screening approach for thalassemia alternative to the OF/DCIP. Based on this approach, the MCV and MCH values obtained from electronic blood cell counters are of important that should be accurate and comparable. To evaluate the accuracy of thalassemia screening using the MCV and MCH measured from different instruments and settings, two quality control (QC) products, the RBC_A (MCV > 80 fl and MCH > 27 pg) and RBC_B (MCV < 80 fl and MCH < 27 pg), were prepared and sent to 13 participated laboratories. Rbc parameters of each QC product were measured routinely in each laboratory. By comparing to the initial values obtained in our laboratory, it was found that all Rbc parameters of the two QC products were accurately measured with the coefficient of variation (% CV) of 2.09 - 9.76 % for RBC_A and 1.11 - 11.04 % for RBC_B. Regarding to the instruments, the % CV of most Rbc parameters were less than 2 % for both RBC_A and RBC_B. To evaluate the accuracy of the MCV and MCH in application to thalassemia screening, the MCV cutoff value of 80 fl and MCH cutoff value of 27 pg were applied. The RBC_A was treated as negative sample and the RBC_B was treated as positive sample. By using the MCV approach, false negative results were obtained form 2 laboratories. In contrast, neither false negative nor false positive result was found with the MCH approach, suggesting that MCH might be more appropriate for thalassemia screening than MCV. The results indicate that these QC products might be used as an internal QC to evaluate the accuracy of Rbc parameters and as an external QC to evaluate the performance of thalassemia screening using the MCV and MCH approaches of each laboratory setting.