Multivariable adjustment
In the multivariable Cox regression analysis with in-hospital
death as the dependent variable, higher hemoglobin
concentrations (relative risk (RR) = 0.97, 95% confidence
interval (CI) = 0.95 to 0.98, per 1 g/dl, P≤0.001) and
receipt of a blood transfusion (RR = 0.96, 95% CI = 0.92 to
0.99, P = 0.031) were independently associated with a
lower risk of in-hospital death [see Table S4 in Additional
file 1].