Correction to: BMC Anesthesiol 21, 29 (2021)

https://doi.org/10.1186/s12871-021-01245-5

Following publication of the original article [1], the authors report an error in the Method section. The formula used for determining the cut-off points from the receiver operating characteristic (ROC) curves was published incorrectly, so the authors correct the error. The formula was published as below originally.

$$d=\sqrt{{\left(1-sensitivity\right)}^{2}+{\left(1-sensitivity\right)}^{2}}$$

The authors correct this as below [2].

$$d=\sqrt{{\left(1-sensitivity\right)}^{2}+{\left(1-specificity\right)}^{2}}$$