Sample size: The power calculation is based on a pilot study of IQCODE. The study that included 32 75-year-olds from geriatric ward at Aarhus University hospital, showed an no incidence of delirium of when the IQCODE-score was ≤3,125. On the contrary the incidence of delirium was 15% when the IQCODE-score was >3,125. With a power of 90% and a significance level of 5%, 76 patients should be included in each group to predict delirium.