Applications of international blood smear review criteria for improvement on Beckman-Coulter hematology analyzers

Abstract

Objective To evaluate the international blood smear review criteria for improvement using Beckman-Coulter hematology analyzers and find out proper slide review criteria suitable for Chinese population. Methods 3 600 random-selected blood samples were tested in three hospitals using MAXM, GENS and LH750 5-diff automated analyzers and a manual differential with a smear review was performed on all samples in the study. True positive rate, true negative rate, false positive rate and false negative rate were calculated according to the international blood smear review criteria. We have set up smear review criteria for Chinese population by analyzing false positive and false negative cases according to Chinese clinical conditions. Another 240 blood samples were tested in three hospitals using the same analyzers to verify the new slide review rules. Results According to international blood smear criteria, the true positive rate was 4.9%, false positive rate was 24.2%, true negative rate was 70.4% and false negative rate was 0.5%. The international smear review criteria were modified into 23 criteria by analysis of above statistical data. In addition, we added four WBC differential ratio rules in positive smear criteria. After modification, the true positive rate was 9.9% (355/3 600) ,false positive rate was 17.1% (617/3 600), true negative rate was 71.2 % (2 563/3 600) and false negative rate was 1.8% (65/3 600). No blast cell was missed using both smear review criteria. A little higher false negative rate after modification was caused by supplemented differential ratio roles in positive smear criteria. Verification results were satisfactory;The tree positive rate was 13.7% (33/240) ;false positive rate was 15.8% (38/240) ;false negative rate was 2.5% (6/240) and true negative rate was 68.0% (163/240). Conclusions Although the smear review criteria suggested by the International Consensus Group is clinically important, the false positive rate increases when they are used in Chinese population. The modified slide review criteria used on Beckman-Coulter hematology analyzers in this study are more suitable for Chinese laboratories. Key words: Blood cell count; Hematologic tests; Diagnostic equipment ; Autoanalysis; Evaluation studies