An intralaboratory evaluation of the Coulter S+II lymphocyte percent (CLy%) as indicative of actual lymphocyte numbers in blood.

A field trial of the medical significance and possible error rate associated with the Coulter S+II lymphocyte percent was performed by comparing 1,500 sequential differentials performed on Geometric Data Hematrak instruments to the results of Coulter volume displacement enumeration of lymphocytes on three S+II instruments. The results of this study indicate that a statistically significant but medically insignificant bias is present between lymphocyte counting technics, that the statistical imprecision of the determination of lymphocytes by the Coulter lymph percent (CLy%) falls within the expected range for statistical inaccuracy of determination of lymphocytes by manual differential technics and that in virtually all cases no medically significant errors would result from accepting the CLy% as indicating the actual numbers of lymphocytes present, as all blood specimens with medically significant abnormalities would have had manual differential and slide review triggered by other abnormalities in the blood count results. The Coulter lymph percent is a useful addition to the other complete blood count parameters.