50 B. D. HEDLEY ET AL. DXH 800 PERFORMANCE EVALUATION Table 2. Accuracy P values, bias (mean difference), and % mean difference for the DxH 800 cellular analysis system vs. the LH 780 and ﬂow cytometry (FCM) Parameter Subset WBC WBC WBC PLT PLT PLT PLT None Cellular Interference NRBC None <50 · 109/l Giant Platelets Microcytosis DxH 800 vs. LH 780 DxH 800 vs. FCM P value 0.762 0.782 0.879 0.716 0.784 0.812 P value (w/o ﬂags) 0.858 0.799 0.931 0.625 0.833 0.773 0.605 Bias 0.51 0.42 0.69 )8 0.24 )27 )12 2 4 3 )7 24 )4 )4 % Diff P value 0.693 0.654 0.736 0.510 0.276 0.640 P value (w/o ﬂags) 0.754 0.642 0.762 0.657 0.831 0.640 0.987 Bias 0.59 0.57 0.73 )16 )0.07 )12 1 % Diff 6 8 6 )9 )7 )17 )5 WBC, white blood cell; PLT, platelet; NRBC, nucleated red blood cell. (r2 = 0.990) in this subset (Figure 1b). These highly correlative results were also accurate (showing no statistical difference) when the DxH 800 was compared to the LH 780 (P = 0.782) and FCM (P = 0.654). WBC count comparison of the DxH 800 in samples determined to have NRBCs revealed that the DxH 800 correlates well with both the LH 780 and FCM (Fig- ure 1c, r2 = 0.998 and r2 = 0.992, respectively). The DxH 800 detects and compensates well for the presence of interference to accurately enumerate WBCs without signiﬁcant bias (see Table 2), The number of samples with ﬂagged WBC values was sim- ilar between the DxH 800 and the LH 780 (4% and 3%, respectively). RBC parameters A new feature of the DxH 800 is the automated cor- rection of hemoglobin when the UWBC is 11 · 109/ l. Correction is also performed, as appropriate, on other parameters (RBC count, MCV, and RDW) when the UWBC is 140 · 109/l. A set of eight samples had WBC counts 140 · 109/l and were reviewed closely to determine the difference between the corrected counts on the DxH 800 and the standard laboratory method of handling extreme leukocytosis and the erroneous impact on red cell analysis. Results from the calculations detailed in the materials and methods section and from the DxH 800 are shown in Table 3. As can be seen, the hemoglobin, red blood cell count, Table 3. Evaluation of the DxH 800 automated RBC correction compared to manual RBC correction on high white blood cell (WBC) counts WBC (·109/l) 161.2 101.8 114.3 149.1 137.1 120.1 108.1 208.6 Red cell (·1012/l) DxH 2.45 3.23 3.12 4.00 4.08 3.72 2.74 3.35 Manual 2.42 3.16 2.90 3.84 3.79 3.47 2.73 3.33 count Hemoglobin (g/l) Mean cell volume (ﬂ) DxH 84.0 96.9 104.1 122.0 123.4 112.0 77.8 110.8 Manual 81.0 100.0 102.0 122.0 119.0 114.0 83.0 108.0 DxH 99.69 100.56 109.16 92.20 98.06 99.03 86.00 98.16 Manual 97.5 98.3 102.4 88.3 92.0 91.4 83.8 95.5 RDW (%) DxH 14.56 17.26 15.01 16.29 14.08 13.48 15.58 15.58 Manual 14.7 18.1 15.5 16.6 14.1 13.6 16.2 15.1 2010 Blackwell Publishing Ltd, Int. Jnl. Lab. Hem. 2011, 33, 45–56