Delirium, how does it end? Mortality as an outcome in older medical inpatients

Abstract

Objectives: Delirium is associated with poor outcomes. Previous research in delirium and mortality gave rather inconclusive results. This study aims to find out the rates of mortality at 1 year and the factors associated with it in a cohort of hospitalized older patients.

Method: Prospective, observational, longitudinal study. All acute medical admissions 70 years of age and above were approached within 72 h of admission. Exclusion criteria are as follows: severe aphasia; intubation; severe sensory problems; and non-English speakers. Patients eligible for inclusion were assessed four times, twice weekly during admission. Delirium was defined using the Confusion Assessment Method.

Results: Two hundred patients were recruited. The mean age was 81.13 years (SD = 6.45; minimum 70 and maximum 100 years old), of which 100 (50%) participants were women. One hundred fifty-four (77%) patients never developed delirium during hospitalization. The overall rate of delirium was 23%. A total of 55 (27.5%) patients died during the 1-year follow-up. Although at 1-year follow-up, more people with delirium died (χ(2) = 9.873, df:1, p = 0.002), survival analysis after controlling for other variables showed that mortality was independent of delirium and that severity of illness, longer hospital stay and cognition were significant risk factors for mortality.

Conclusion: Although the sample size precludes drawing any definite conclusion, the findings of this study suggest that delirium is not an important risk factor for subsequent mortality. Perhaps delirium and cognitive impairment share common pathophysiological pathways that are related to mortality and in which the currently used methods cannot detect.

Keywords: cognition; delirium; length of hospital stay; mortality; outcomes; severity of illness.