[Evaluation of the System 9000-AX autoanalyzer]

The aim of this study was to evaluate the haematologic autoanalyser System-9000 AX (Serono-Baker Diagnostics), which provides 15 parameters of red, white and platelet series and three histograms showing the cellular distribution curves according to the volume of each series.

The accuracy, precision, linearity, carry-over, effective speed and the effect of sample storage on results were studied. Moreover, the leucocyte differential count (LDC), false positive and negative results of the automated differential count and sensitivity, specificity and efficiency of LDC were analysed and compared with conventional methods: a Coulter VCS analyser and a Coulter S-Plus STKR.

The accuracy of the results of three haematologic series was very good. In the LDC, the results for the middle and big cells were better in comparison with the manual method (r > 0.80) than the Coulter VCS, (r = 0.28 and 0.48 respectively). The percentage of LDC revisions and the false negative was higher in hospitalized patients than in outpatients (28.14 and 8.46% versus 12.56 and 2.18%). The most common anomalies were the left deviation, monocytosis and eosinophilia. The results of sensitivity, specificity and efficiency were greater than 80% in all cases, except for the sensitivity and efficiency of hospitalized patients, because of the greater number of false negatives. Precision and linearity were excellent in all the parameters studied. No significant contamination was observed among the samples (low carry-over percentage). The samples were stable for 24 hours at 4 degrees C.

The System 9000 AX is a reliable analyser, which is fast and easy to operate. These characteristics allow this analyser to be a very useful tool for laboratories that require a rapid testing of samples.