Comparison of four methods to measure haemoglobin concentrations in whole blood donors (COMPARE): A diagnostic accuracy study.Bell S, Sweeting M, Ramond A, Chung R, Kaptoge S, Walker M, Bolton T, Sambrook J, Moore C, McMahon A, Fahle S, Cullen D, Mehenny S, Wood AM, Armitage J, Ouwehand WH, Miflin G, Roberts DJ, Danesh J, Di Angelantonio E, COMPARE Study Group.
