Validity of the haemoglobin colour scale in blood donor screening

The haemoglobin colour scale (HCS) has been developed as a simple, reliable and inexpensive clinical device for diagnosing anaemia and estimating its severity when laboratory-based haemoglobinometry is not available. The purpose of this study was to assess its validity for screening blood donors for anaemia.

The HCS was tested at five blood transfusion centres on a total of 2801 donors. Blood was obtained by skin puncture as part of the routine procedure at the donor sessions. HCS readings were compared with screening by the copper sulphate method, which was in routine use in the centres, and with haemoglobin (Hb) measurements by means of calibrated HemoCue haemoglobinometers. HCS readings were considered as normal when the readings were > or = 12 g/dl.

Analysis of the paired results showed that the HCS had an accuracy of 97.5% in distinguishing subjects with normal Hb from those below the acceptable limit, when checked against the HemoCue. The HCS was more reliable than the copper-sulphate specific-gravity method, yielding 3.7% false readings compared with 6.1% false readings, respectively. When discrimination was set at 12 g/dl with the HemoCue, the HCS gave an incorrect reading in 2.4% of donors. The majority of these false results (44 donors; 1.58%) were caused by the HCS indicating rejection of the donor (i.e. Hb < 12 g/dl) when the correct Hb was higher, whilst in 23 donors (0.82%) the HCS incorrectly indicated a normal Hb; however, in all but four of these donors the correct Hb values were 11.0-11.9 g/dl, and none were below 10 g/dl.

The operators were able to master the HCS technique after a few minutes of practice, and all found the test to be user friendly and easy to read. The HCS is proposed as a replacement for the copper sulphate method for blood transfusion donor selection.