Symptoms and aetiology of delirium: a comparison of elderly and adult patients.

OBJECTIVE. To compare the symptoms of delirium as assessed by the Delirium Rating Scale-Revised-98 (DRS-R-98) and associated aetiologies in adult and elderly patients seen in a consultation-liaison service. METHODS. A total of 321 consecutive patients with a DSM-IV-TR diagnosis of delirium were assessed on the DRS-R-98 and a study-specific aetiology checklist. RESULTS. Of the 321 patients, 245 (76%) aged 18 to 64 years formed the adult group, while 76 (24%) formed the elderly group (≥ 65 years). The prevalence and severity of various symptoms of delirium as assessed using the DRS-R-98 were similar across the 2 groups, except for the adult group having statistically higher prevalence and severity scores for thought process abnormalities and lability of affect. For both groups and the whole sample, factor analysis yielded a 3-factor model for the phenomenology. In the 2 groups, the DRS-R-98 item loadings showed subtle differences across various factors. The 2 groups were similar for the mean number of aetiologies associated with delirium, the mean number being 3. However, the 2 groups differed with respect to hepatic derangement, substance intoxication, withdrawal, and postpartum causes being more common in the adult group, in contrast lung disease and cardiac abnormalities were more common in the elderly group. CONCLUSION. Adult and elderly patients with delirium are similar with respect to the distribution of various symptoms, motor subtypes, and associated aetiologies.