Jeroen MALFAIT1, Melanie VANTIEGHEM1, Stephane ROUGALE2, Majda MAYEMI SAIFI2, Marlène REYNAUD2 and Veronique STOVE1
1 Department of Laboratory Medicine, Ghent University Hospital, Belgium; 2 HORIBA Medical, Montpellier, France
Background
The Pentra XLR is a new generation of Pentra analytic systems, able to perform the cell blood count (CBC) , a 5‐part leukocyte differential (5 DIFF) analysis and a reticulocyte count.
The CBC and 5 DIFF are based on impedance, cytochemistry and the measurement of light absorbance, using the double‐hydrodynamic sequential system (or DHSS) technology. On the Pentra XLR, the flow cytometric reticulocyte analysis (RET) is performed by use of the thiazole orange dye. Young, immature reticulocytes are brightly fluorescent while maturing reticulocytes show an intermediate or low fluorescence intensity. Automated counting of reticulocytes has increased the accuracy and precision compared with traditional manual counts and provides the ability to reliably measure new parameters of RET maturation, such as immature reticulocyte fraction (IRF) and measurement of the reticulocyte hemoglobin content.
The aim of the present evaluation is to determine the analytical performance of the new Pentra XLR blood cell analyzer. The results provided by this instrument were compared with those obtained by our routine hematology analyzer. Moreover, RET results were compared with a reference method on a three laser flow cytometer.
Materials and methods
The study consisted of a performance qualification.
Blood samples
Blood samples (K2‐EDTA) from our daily routine were used for CBC + DIFF (n =135) and RET (n=213) analysis. The samples were selected to have 50% as normal and 50% with pathologies, based on the expert rules of our routine hematology analyzer.
Performance qualification
- Reproducibility: this protocol follows the CLSI EP5‐A2 guideline. The reproducibility is done on 3 control levels: low, normal and high with ABX Difftrol for DIFF mode and ABX Minotrol Retic for RET mode, with 4 runs/day/level.
- Repeatability: within‐run imprecision was evaluated based on 12 consecutive measurements on 4 samples that were assayed in RET mode. The test was performed on normal blood.
- Accuracy / method comparison: coefficients of determination and Passing and Bablok regression analysis were used to evaluate agreement of Pentra XLR with the XE‐5000 analyzer (Sysmex) for CBC+DIFF+RET analysis, and the BD Retic‐Count™ kit on the BD FACSCanto II flow cytometer (Beckton Dickinson) for RET analysis.
Results of CBC + 5 DIFF
Imprecision reproducibility
Run‐to‐run imprecision results are shown in Table 1 for CBC+DIFF, and Table 3 for RET parameters. All results were within the specifications established by the manufacturer.
| | | CBC count | 5 DIFF count |
|---|
| | | WBC
109/L | RBC
1012/L | HGB
g/dl | HCT
% | PLT
109/L | LYM
109/L | MON
109/L | NEU
109/L | EOS
109/L | BAS
109/L |
|---|
| Low | Mean value
Obtained CV %
Expected CV % | 2.33
2.74
5.00 | 2.44
2.01
3.00 | 6.56
1.79
2.50 | 19.80
2.56
5.00 | 66
6.18
15.00 | 0.69
7.01
8.00 | 0.04
28.10
40.00 | 1.35
3.91
8.00 | 0.18
23.36
25.00 | 0.07
5.77
8.00 |
|---|
| Normal | Mean value
Obtained CV %
Expected CV % | 7.08
2.00
4.00 | 4.75
2.13
2.50 | 13.63
1.54
2.00 | 38.80
2.39
4.00 | 256
4.01
10.00 | 2.22
4.07
8.00 | 0.19
9.79
20.00 | 4.05
2.72
6.00 | 0.37
13.02
15.00 | 0.24
3.67
8.00 |
|---|
| High | Mean value
Obtained CV %
Expected CV % | 16.66
1.68
3.00 | 5.31
1.84
2.50 | 16.58
1.36
1.80 | 46.53
2.19
3.00 | 521
2.34
7.00 | 2.72
3.49
8.00 | 0.48
11.06
15.00 | 11.77
1.98
4.00 | 0.97
7.61
10.00 | 0.72
2.54
8.00 |
|---|
Table 1: Reproducibility of complete blood cell count (CBC), 5 DIFF count on new Pentra XLR analyzer.
Correlation DIFF mode
The comparison between the Pentra XLR and XE‐5000 was performed on 135 samples. A high degree of agreement between the 2 methods Pentra XLR and XE‐5000 was observed, as estimated by the coefficient of determination regarding RBC, WBC, HCT, HGB, LYM and PLT , R² ≥ 0.95 (Figures 1‐4).
