Comparability of haematology profile between QBC (R) Autoread (TM) Plus System and all electronic cell counting instrument (Coulter Counter STKS)

Aim: To evaluate whether the QBC(R) Auto-read(TM) Plus System (QBC = Quanti tative Buffy Coat analysis) is suitable for assessment of a complete blood cell count. Method: The QBC(R) Autoread(TM) Plus System is a method for determining a n ine parameter haematology profile including a WBC differential count of cen trifuged or capillary blood. It is based on electrico-optical linear measur ements of the discrete layers of packed blood cells in a microhaematocrit t ube. The study population included 55 healthy individuals and 920 patients. A Coulter Counter STKS was used as a reference instrument. Results: Of a total of 920 probes, 70 had to be excluded due to delayed ana lysis. Out of 850 probes 5.6% were unreadable. Good precision was noted for haemoglobin and haematocrit (CV 1% and 2.2% respectively), as opposed to t he other parameters (CVs ranging from 10.5 to 16.6%). Good accuracy was see n for haemoglobin and haematocrit (R-s 0.982 and 0.955, slope of linear reg ression 1.0 and 0.99, y-distance 0.40 g/l and 0.56% respectively). In contr ast, values for granulocytes and mononuclear cells (lymphocytes, monocytes) were inaccurate (R-s each 0.650, slope 1.53 and 0.77, y-distance -0.76 10( 9)/l and -0.27 10(9)/l respectively). Particularly inaccurate values were s een for leukocyte counts of children suffering from haematological diseases and of children treated in the emergency unit (R-s 0.688 and 0.607, slope 1.09 and 1.43, y-distance -0.02 10(9)/l and -2.95 10(9)/l). In the whole st udy population acceptable values were noted for platelet counts (R-s 0.833, slope 1.20, y-distance -35.54 10(9)/l). Conclusions: Based on the performance found in our study, the QBC Autoread system cannot be widely recommended for assessment of a nine parameter haem atology profile. It is suitable for measuring haemoglobin and haematocrit a nd acceptable for platelets. It is not reliable for measurements of leukocy tes and the differential count.