Observed incidence rate of postoperative delirium by risk stratification instrument (first author, year of publication) and risk score.

Bars represent 95% confidence intervals. Dashed lines correspond to an incidence rate of 25%. * 95% confidence interval omitted because category included only one person. ** For the risk stratification instruments of Inouye (1993), Marcantonio (1994), Pompei (1994), Martinez (2012), and Kobayashi (2013) the cut-off point was defined by the authors of the original study. For the definition of the cut-off points of the other risk stratification instruments, see text. For the number of persons per risk score, see Table S2.