Allostatic Load and Delirium among Hospitalized Elders

Delirium is a state of acute confusion and is common in hospitalized older adults. Delirium is associated with significant increases in morbidity and mortality, as well as healthcare costs. Delirium also is associated with functional and cognitive decline, as well as need for institutionalization and rehabilitation. Delirium can cause psychosocial distress for patients and families. While much is understood about the epidemiology of delirium, the pathophysiological mechanisms that lead to the development of delirium are less clearly defined.The purpose of this study was to investigate the relationship of allostatic load (AL), a composite measure of primary (i.e. acute) stress mediators and secondary (i.e. chronic) stress outcomes and delirium in the hospitalized older adult. Development of the Allostatic Load & Delirium in Hospitalized Elderly model provided a theoretical framework for the study.Forty- four participants, ranging from 66 to 93 years of age (M = 76 years of age) were recruited from three intensive care units and enrolled once they were determined not to have a cognitive deficit or prevalent delirium, as assessed by the Standardized Mini-Mental State Examination and Confusion Assessment Method (CAM), respectively. Ten AL components reflective of acute and chronic stress were collected upon admission. Allostatic load was calculated as the sum of the number of components for which the participant was rated in the highest risk quartile. Allostatic load subsets based on acute and chronic components were also calculated. Incident delirium was assessed 48 -72 hours after admission with the CAM.Findings indicated that the incidence of delirium was 29.2%. The subset AL score based on components considered primary stress mediators was significantly related to delirium; however, no other variables were associated with delirium. Logistic regression modeling indicated that an AL subset of primary stress mediators did predict the incidence of delirium (OR 2.5, 95% CI = 1.12, 5.79; X2 (1) = 5.668, p < .05).The findings from this study exploring the relationship between AL and delirium in the hospitalized older adult suggest that an AL score based on primary mediators may be useful in predicting delirium in the hospitalized older adult