One hundred and six-teen donors (29%) who failed the CuSO4 test had true Hb levels >12.5 g/dl.
The Hb levels of 131 (32.8%) deferred donors were between 12 and 12.5 g/dl.
The sensitivity of Hemocue, Hb colour scale and Cyanmethemoglobin was 99%, 97% and 96% and their specificity was 45%, 93% and 46%, respectively.
The positive predictive values (PPV) of Hemocue and Cyanmethemoglobin methods were low (43% and 44%, respectively) but their negative predictive values (NPV) were high (99%, and 97%, respectively).
The Hb colour scale had an overall best performance with a PPV of 96% and NPV of 95%.