Our sensitivity analysis regarding the role of unmeasured confounding suggests that, an unmeasured confounder associated with both dementia and delirium with approximate effect sizes of 1.54 each, over and above the measured covariates, could suffice to completely explain away the observed direct effect of one APOE-ε4 copy on delirium, but weaker confounding could not36. The gene discussed is APOE; the disease is delirium.