Systematic comparison of four point-of-care methods versus the reference laboratory measurement of hemoglobin in the surgical ICU setting: a cross-sectional method comparison study

Background Transfusion decision during the perioperative period mostly relies on the point-of-care testing for Hb measurement. This study aimed systematically compared four point-of-care methods with the central laboratory measurement of hemoglobin (LHb) regarding the accuracy, precision, and assay practicality to identify the preferred point-of-care method during the perioperative period. Methods This cross-sectional method comparison study was conducted in the surgical intensive care unit at Ramathibodi Hospital, Thailand, from September 2015 to July 2016. Four point-of-care methods, i.e., capillary hematocrit (HctCap), HemoCue Hb201+, iSTAT with CG8+ cartridge, and SpHb from Radical-7 pulse co-oximeter were carried out when LHb was ordered. Pearson correlation and Bland-Altman analyses were performed to assess the accuracy and precision, while the workload, turnaround time, and the unit cost were evaluated for the method practicality. Results Thirty-five patients were enrolled, corresponding to 48 blood specimens for analyses, resulting in the measured hemoglobin of 11.2 +/- 1.9 g/dL by LHb. Ranking by correlation (r), mean difference (bias) and 95% limit of agreement (LOA) showed the point-of-care methods from the greater to the less performance as followed, iSTAT-LHb pair (r = 0.941; bias 0.15 (95% LOA; - 1.41, 1.12) g/dL), HemoCue-LHb pair (r = 0.922; bias - 0.18 (95% LOA; - 1.63, 1.28) g/dL), SpHb-LHb pair (r = 0.670; bias 0.13 (95% LOA; - 3.12, 3.39) g/dL) and HctCap-LHb pair (r = 0.905; bias 0.46 (95% LOA; - 1.16, 2.08) g/dL). Considering the practicality, all point-of-care methods had less workload and turnaround time than LHb, but only HemoCue and HctCap had lower unit cost. Conclusion This study identified HemoCue as the suitable point-of-care method for the sole purpose of Hb measurement in the surgical ICU setting, while iSTAT should be considered when additional data is needed.