The investigators recently developed the simple 4-question "RACY" delirium screening tool for use in general medical in-patients. Preliminary data show the test to be simple and effective with a sensitivity and specificity of 78% and 85% respectively using a ROC-selected cut-point of RACY≤2. The investigators hypothesis that the RACY screening tool has the potential to be a simple and effective bedside delirium diagnostic instrument for use in non-geriatric, busy general medical in-patient settings. This study is a two-centre validation study to evaluate the diagnostic accuracy of this tool.