Prevalence and evolution of delirium in a community population of 70 years and older

Abstract

Introduction. There are many studies on delirium in clinical populations and nursing home patients but not in community populations. This study has aimed to know the prevalence of delirium in a community population and to know the survival rate during a five-year period.

Method. Case-control and survival study based on data from an epidemiological study to measure the prevalence and incidence of dementia in eight rural villages in Girona. According to the Diagnostic and Statistical Manual of Mental Disorders, delirium was identified for the prevalence study using the information obtained from the Cambridge Mental Disorders of the Elderly Examination. A hypothesis contrast method was used in order to compare all clinical features of the subjects according the presence or the absence of delirium. The Kaplan-Meier technique was used to estimate survival of the subjects, and a multivariate Cox regression analysis was done to know the effect of delirium on mortality over the five-year period.

Results. 1,460 subjects older than 69 participated in the study. A prevalence of 0.96% (95% confidence interval [CI]: 0.43-1.49) was detected (14 cases of delirium). Mean survival for subjects with delirium was 3 years (CI 95%: 1.9-4.1) and it was slightly lower than for healthy controls. The presence of delirium increased the risk of death in five years by 2.65.

Conclusion. The prevalence of delirium in community populations is low and most of the times it is superimposed on dementia. Patients with delirium have a higher risk of mortality at the end of a five-year period.