Prodrome of delirium among long-term care residents: what clinical changes can be observed in the two weeks preceding a full-blown episode of delirium?

Abstract

Delirium among long-term care (LTC) residents is frequent and is associated with increased morbidity and mortality. Identification of clinical changes during the prodromal phase of delirium could lead to prevention of a full-blown episode and perhaps limit the deleterious consequences of this syndrome. The aim of the present study was to identify clinical changes observable in the 2-week period prior to the onset of full-blown delirium. Long-term care (LTC) residents aged 65 years and over, with or without dementia were eligible for this nested case-control study. Delirium was assessed weekly over a 6-month period using the Confusion Assessment Method. Cases with incident delirium were matched by time since enrollment to one or more controls without delirium. When compared to the controls, LTC residents who developed delirium (cases = 85) were more likely to have new-onset perceptual disturbances (OR = 4.75; 95% CI 1.65-13.66) and disorganized thinking (OR = 3.09; 95% CI 1.33-7.19) and a worsening of the Mini-Mental State Examination (MMSE) item measuring registration (OR = 2.59; 95% CI 1.24-5.41) during the preceding 2 weeks. However, the frequency of these changes was low. Residents with at least 3 clinical changes were more likely to develop delirium than those without any clinical change (OR = 2.52; 95% CI 1.08-5.87). This study provides evidence of clinical changes during the prodromal phase of delirium among LTC residents. More studies are needed to further explore the role and relevance of these clinical changes as warning signs of imminent delirium.