A pilot External Quality Assessment Scheme for haemocytometry in Italy

An Italian EQA scheme for haemocytometry, organized by the Istituto Superiore di Sanità, has been active for about five years (1984-1989). The aims of this programme were to evaluate the state of the art and to introduce in Italy a scheme recommended by ICSH. N. 126 public laboratories from different provinces joined voluntarily the programme and trials for haemoglobinometry (A01, A02), full blood count (B01-B08) and platelet count (D01-D03) were performed.

Materials for testing consisted of blood lysate, preserved blood preparation containing native red cells and pseudoleukocytes, suspension of fixed platelets. The performances of laboratories was evaluated by consensus values (median, mean and standard deviation) and individual deviation index.

The instrument survey demonstrated that fully automated systems had the highest frequency. Non Gaussian distributions of results were often obtained and this was particularly true for WBC, PLT and MCV. The overall variability was lower than 5.5% for Hb, RBC and MCH and lower than 9.3% for other erythrocyte parameters; WBC and PLT counts displayed a higher dispersion (CV* = 9.8% and 25.4%); the spreading of results was strongly reduced in the homogeneous group of Coulter counters. In the course of the programme CV*s didn't show any relevant modification, a steady state performance being apparent. As regards the nature of variability, the random component was prevalent for all parameters, with the exception of MCV.

This pilot programme allowed to demonstrate the practicability of a national EQAS for haemocytometry according to the ICSH guidelines. Materials for testing showed acceptable stability, homogeneity and commutability. As regards analytical equipment as well as analytical variability, hospital centers participating in these EQA trials were comparable with laboratories taking part in similar EQAS of other European countries.