HemoCue WBC - Performance Metrics and Method Limitations

40
Specific Performance Characteristics
Linearity
The method used in the HemoCue WBC system has
accor ding to the CLSI Document EP6-A been dem-
onstrated to be linear between 0.3–30.0 x10
9
/L
(300–30000/mm
3
, 300–30000/µL), within 0.2 x10
9
/L
difference in 0.3–3.5 x10
9
/L and within 6 % difference
in 3.6–30.0 x10
9
/L.
Within-run and Total Precision
Within-run and Total Precision was determined accor ding
to the CLSI Document EP5-A2. The results given below
come from four batches of HemoCue WBC Microcu-
vettes, and five HemoCue WBC Analyzers. Commercially
available controls at three different levels were used. The
WBC count was measured in duplicate twice a day, morn-
ing and afternoon, during 20 consecutive days.
Level N x10
9
/L Within-run
Precision
CV %
Total
Precision
CV %
1 400 2.5 4.1 5.4
2 400 7.2 2.9 3.5
3 400 19.0 1.6 1.9
Additionally, a study has been performed to determine
the precision using fresh blood samples. The study was
performed on venous whole blood samples tested in
duplicate.
x10
9
/L N CV
duplicates
%
Sysmex XS-1000i HemoCue WBC
0.3–1.0 12 5.0 10.4
1.1–3.5 52 3.7 4.1
3.6–10.0 209 1.9 3.5
10.1–20.0 88 2.1 2.5
20.1–30.0 35 1.8 2.2
Total 396 2.4 3.2