Reference values in haematology. A survey in Italy: report from Latium.
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Biomedical subjects
Publications and source records attributed to A M Salvati.
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The relative accuracy and precision of the Coulter S Counter have been evaluated in comparison with manual hemiglobincyanide determination according to the recommendations of the International Committee for Standardization in Hematology. Some improvements in the manual procedure, such as centrifugation of hemiglobincyanide solutions and the use of the detergent Triton X-100, were also tested. The Coulter S Counter generally gives higher precision in comparison with the manual method. Nevertheles, Coulter S determinations are systematically lower due to both constant and proportional errors. The available data ranged between hemoglobin values of 11.5 and 18.5%, giving differences of 0-8% between hemoglobin values determined by the Coulter S Counter and the hemiglobincyanide method.
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BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.
BACKGROUND AND METHODS: The operating performance of the Coulter Counter S Plus STKR was evaluated in two hospital laboratories in Rome and in Florence. Experimental design conformed to both the ICSH and NCCLS Standards for the evaluation of hematologic analyzers, and to the ECCLS guidelines for the multicenter evaluation of analyzers in clinical chemistry. RESULTS AND CONCLUSIONS: Cell counts in K3 EDTA were unchanged over 6 hours at room temperature and 72 hours at 4 degrees C, while MCV, MPV and leukocyte differentials were far less stable. Carry over, precision and linearity met the manufacturer's specifications, while a satisfactory relative accuracy was demonstrated by determining reference values on an adult reference group and by comparing the instrument with the previous model S Plus IV D. The accuracy of the leukocyte differentials was evaluated by the microscope reference method, and our results seemed to validate the hypotheses that the STKR model counts: i) eosinophils, basophils and banded neutrophils among GR; ii) variant lymphocytes among LY, and iii) various abnormal cells among mononuclear cells. However, in spite of this statistical significance, some difficulties in correctly classifying the mononuclear population were demonstrated.
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