None of the additional confounders had an independent OR effect on both delirium and dementia above 1.54 each, the minimum required to explain away the observed APOE direct effect on delirium; however, some residual confounding may still remain, for example due to precipitating factors of delirium episodes during hospitalization, such as infections, medication status, sleep disruptions or severity of presenting illness. The gene discussed is APOE; the disease is infection.