Associations of delirium with in-hospital and in 6-months mortality in elderly medical inpatients

Age Ageing. 2007 Nov;36(6):644-9. doi: 10.1093/ageing/afm094. Epub 2007 Jul 28.

Abstract

Background: Studies on the association between mortality and delirium in older hospital inpatients have produced conflicting results. This insconsistency might be explained by case-mix differences in terms of clinical or underlying patho-physiological processes. For example, both albumin and C-reactive protein (CRP) have been reported as predictors of in-hospital mortality and interleukin-6 of longer-term mortality.

Methods: We used data from a longitudinal study of delirium to investigate the delirium-mortality relationship. A cohort of 164 patients, 70+ years were assessed within 3 days of acute hospital admission and hence twice weekly until hospital discharge, for the presence and severity of delirium and a range of clinical and laboratory measures, including initial albumin (n = 149), CRP (n = 76) and cytokine (n = 60) levels. In-hospital and 6-months mortality were determined from clinical records and telephone contact.

Results: During hospitalisation 14 (8.5%) patients died, 6 with delirium: mortality was not associated with delirium. At 6 months, 119 of 150 (77.3%) discharged patients were still alive, 21 (14.0%) dead, and 13 (8.7%) uncontactable. In bivariate analysis, 6-months mortality was associated with older age (P = 0.013), lower albumin (P = 0.001), higher CRP (P = 0.014) and higher interleukin-6 levels (P = 0.007), but not with presence or severity of in-hospital delirium. After controlling for other variables significant predictors (P < 0.05) for six-month mortality were initial MMSE, albumin, interferon-lambda and interleukin-6.

Conclusions: The lack of demonstrable association between delirium and mortality may reflect inadequate statistical power in this study due to low numbers. These findings, however, highlight specific patho-physiological factors which may be important in the prognosis after delirium.

MeSH terms

  • Age Factors
  • Aged
  • Aged, 80 and over
  • Albumins / metabolism
  • Biomarkers / blood
  • C-Reactive Protein / metabolism
  • Data Interpretation, Statistical
  • Delirium / blood
  • Delirium / mortality*
  • Female
  • Hospital Mortality / trends*
  • Humans
  • Inpatients / psychology*
  • Interleukin-6 / blood
  • Logistic Models
  • Male
  • Predictive Value of Tests
  • Prognosis
  • Prospective Studies

Substances

  • Albumins
  • Biomarkers
  • Interleukin-6
  • C-Reactive Protein