DISCRIMINANT-ANALYSIS OF MACROCYTIC RED-CELLS

Laboratory classification of red cell disorders uses the red cell indi ces (MCV, MCH, MCHC, RDW) and information gleaned from microscopic eva luation of a blood film. Additional red cell information is now availa ble using the H series of automated blood cell analysers (Ames Technic on Division of Bayer Diagnostics). This study involved the development of a discriminant rule which would differentiate between three causes of macrocytosis (vitamin B-12/folate deficiency, alcohol excess/liver disease and a reticulocytosis) using the information available on Res earch Screen 1 and Report Screen 3 of the H1 instrument (Report Scree n 3 is a graphical display of the trimmed scattergram of red cell volu me and red cell haemoglobin concentration and Research Screen 1 displa ys the associated numerical data). Three methods of analysis were asse ssed to define a suitable; discriminant rule. The percentages of patie nts correctly classified by the three methods were: 92.1%, 82.0% and 8 9.2% for Methods 1, 2 and 3 respectively. Method 1 involved the applic ation of quadratic discrimination to transformed variables and produce d the best results. Although complex, it could easily be applied using the microprocessor capability of the average multiparameter haematolo gy analyser.