Evaluation of new non-invasive & conventional invasive methods of haemoglobin estimation in blood donors

The non-invasive method of haemoglobin (Hb) estimation has unique advantages of exemption of finger prick and associated pain, over invasive methods. This study was done to compare invasive and non-invasive methods of Hb estimation in blood donors keeping haematology analyzer (HA) as a reference method.

The blood donors selected or deferred on the basis of CuSO₄method (Hb ≥12.5 g/dl), were included in the study. Hb values of the donors were estimated by HemoCue and then by OrSense methods. An immediate post-donation venous sample was drawn for analysis on HA.

The mean Hb value was 13.98±1.27 g/dl on HA, 14.87±1.03 g/dl on OrSense and 15.03±1.31 g/dl on HemoCue. CuSO₄, HemoCue and OrSense demonstrated sensitivities of 18.7, 18.7 and 13.1 per cent, positive predictive values (PPV) of 64.5, 83.3 and 60.9 per cent and specificities of 98.9, 99.6 and 99.1 per cent, respectively. The intra-class correlation coefficient for OrSense was 0.726 while that for HemoCue was 0.851. Bland-Altman plots demonstrated 2SD difference of >2.0 g/dl in Hb estimations between HA and HemoCue/OrSense.

The non-invasive modality may provide the near-ideal pre-donation Hb screening platform if an improvement can be done in the sensitivity and PPV of the non-invasive method keeping in view its unique advantages.