APOE and delirium: Participants with ≥1 APOE ε4 allele were more likely to develop delirium (e.g., ε4ε4 hazard ratio = 3.73, 95% confidence interval 2.68–5.21, p = 8.0 × 10−15 compared to ε3ε3), but there was no interaction with vitamin D variants.