APOE and delirium: Finally, a mediation analysis further adjusting for cognitive function, socioeconomic deprivation and chronic disease burden, on top of age and sex, still detected a significant direct effect of APOE-ε4 on delirium: OR direct effect (0vs1) 1.12, 95% CI 1.01–1.25; P = 0.038 (32% of the total effect) for one APOE-ε4 copy and OR direct effect (0vs2) 1.55, 95% CI 1.18–2.06; P = 2 × 10−3 (34% of the total effect) for two APOE-ε4 copies, respectively (Extended Data Fig. 7).