2.5. Precision study

All devices (Haemospect, HemoControl, and Sysmex XE‐2100) were well calibrated and controlled; manufacturers’ instructions were followed while performing the Hb measurement. The HemoControl was calibrated with the manufacturers’ calibration cuvette (Hb value was 15.6 g/dL) during the study period.

To investigate the precision of the venous method and the invasive POCT device, two levels of commercial quality control materials for each device were analyzed. For the noninvasive POCT method, two healthy volunteers (their Hb values were stable) who did not participate in the blood donation process were included in the analysis of within‐day and between‐day imprecision. The palm side of the fingers of these subjects was measured by the noninvasive POCT device. The within‐day and between‐day CVs were calculated. The within‐day CV's of the Haemospect, the HemoControl, and the Sysmex XE‐2100 were 7.08, 2.45, and 1.04 at 11.8, 6.3, and 7.9 g/dL concentrations; 3.2, 1.28, and 1.22 at 18.0, 13.0, and 13.9 g/dL concentrations, respectively. The between‐day CV's of the Haemospect, the HemoControl, and the Sysmex XE‐2100 were 4.37, 1.81, and 1.02 at 11.8, 6.3, and 5.8 g/dL concentrations; 4.42, 1.69, and 0.82 at 18.0, 13.0, and 12.4 g/dL concentrations, respectively.

The allowable total analytical error (TEa) was calculated using internal and external quality control results according to Ricos C. et al study11 for the venous method, served as a reference and the obtained 4.09% value was under the TEa limit of Hb (±7%).12 TEa of the POCT devices were not calculated because there were no external quality control materials for the POCT devices.