Review criteria for automated hematology analyzers / 中华检验医学杂志

ABSTRACT

Since 1956 when Wallace Coulter developed a first automated analyzer for counting and sizing cells,the microscopic complete blood count(CBC)and WBC differentiation method has been revolutionized by modern multi-parameter analyzers.Flagging properties in these analyzers can alert the operator to the existence of abnormalities. Microscopic examination of a stained blood film is used to complement analyzer results to provide a comprehensive hematology report.Now it is recognized that the automated systems are superior for counting WBC,RBC and platelets and for differential counting of WBC for mature cell types,whereas visual microscopy is superior for differentiating cells based on nuances of cytological features,especially for immature cells.Therefore the decision as to whether smear review is necessary for each sample plays a major role in hematology laboratory operations.For many samples,we need only review smears to provide information additional to or missing from analyzer results,or to confirm results produced by the analyzer. Each laboratory has developed its own criteria for action after an automated analysis of a blood sample. The objective is to reduce the number of samples unnecessarily requiring action such as smear review(false positives)to the greatest possible extent,while not endangering the patient by reporting false or misleading results(false negative results).However,there is little opportunity for an individual laboratory to know whether the rules it follows are optimally effective for minimizing false negatives and false positives.At the initiative of Dr.Berend Houwen,an international group of experts set up their criteria for review following automated hematology analyzer results and published International Hematology Consensus Group rules for action.These publications also contain guidelines to enable any laboratory to validate rules for action following automated hematology analyzer results. In general,the rules for action should be commonly used in all laboratories because a uniform standard of performance can be achieved by all participating laboratories if they follow these guidelines.In addition,a much larger and more comprehensive set of data can be obtained by combining data from many laboratories. When the consensus rules were compared with the rules of each of the participating laboratories in Consensus Group,there was improvement to a greater or lesser extent in every laboratory.Information from other laboratories now using these rules is that hematology laboratory operations have been improved. Although it has not been confirmed yet,the International Group's consensus rules could be applicable for all laboratories.But there are definite cautions which depend on the analyzers.It is likely that the physiology based rules would be applicable to patients worldwide;however,because the rules were just tested on patients from countries in the Consensus Group and there was no Asian participation in the group, we have no knowledge whether different prevalence of different diseases in Asia might affect applicability and suitability of certain rules. For those rules that are analyzer-based,especially those based on analyzer flags,some differences could be expected due to the differences in flagging sensitivity and efficiency for different manufacture's products. The Consensus Group recommends that any laboratory wishing to use the guidelines perform validation testing in its own situation first.In the country of China,it might be advantageous for testing and potential subsequent modification of the guidelines,for this to be performed under the guidance and control of a national body,such as the Chinese Society for Laboratory Medicine. No three part WBC differential analyzers were included in the Consensus Group study.Of the 41 rules, probably no more than 16 of them would be applicable to three part WBC differential analyzers as written; and these would have to be validated for the characteristics and performance of the WBC,RBC and platelet channels of three part WBC differential analyzers.Other rules could be developed for three part differential analyzers using a similar approach to that used by the International Consensus Group and making use of the suggested procedures included in the publications.The Chinese Society for Laboratory Medicine might consider establishing a Consensus Group of Chinese experts to develop guidelines for national use.