Underdiagnosis of delirium on admission and prediction of patients who will develop delirium during their inpatient stay: a pilot study

INTRODUCTION The study aimed to determine the prevalence and documentation of delirium among the elderly and if the Clock Drawing Test (CDT) can be used to predict which patients had delirium on admission and those who may develop delirium during their stay in acute medical wards. METHODS A single researcher performed the Mini-Mental State Examination (MMSE) and CDT on admission and discharge of 57 elderly adults at the National University Hospital, Singapore. Delirium was defined as a >= 3-point improvement or >= 2-point decline in MMSE scores from admission to discharge, where a fall denotes development of delirium and a rise denotes resolution. The case notes of the same patients were reviewed for documentation of delirium. All inpatients from two acute medical wards were examined. One CDT score and a pair of MMSE scores were collected from each patient. RESULTS A total of 57 patients (28 male, 29 female) were involved in the study. Their mean age was 76.0 +/- 8.7 years. The prevalence of delirium based on MMSE scores was 40.4%; 16 patients had delirium on admission while seven developed delirium during their inpatient stay. However, delirium was documented in the case notes of only 7 (30%) of the 23 patients. CDT score was better than baseline MMSE score at predicting a decline in MMSE score. CONCLUSION The prevalence of delirium in the acute medical setting is high but underdiagnosed. The CDT may be a good screening tool to identify patients at risk of delirium during their inpatient stay. Baseline cognition screening should be performed in every elderly patient admitted to hospital.