Association of Delirium With Long-term Cognitive Decline

Delirium is associated with increased hospital costs, health care complications, and increased mortality. Long-term consequences of delirium on cognition have not been synthesized and quantified via meta-analysis.

To determine if an episode of delirium was an independent risk factor for long-term cognitive decline, and if it was, whether it was causative or an epiphenomenon in already compromised individuals. Data Sources: A systematic search in PubMed, Cochrane, and Embase was conducted from January 1, 1965, to December 31, 2018. A systematic review guided by Preferred Reporting Items for Systematic Reviews and Meta-analyses was conducted. Search terms included delirium AND postoperative cognitive dysfunction; delirium and cognitive decline; delirium AND dementia; and delirium AND memory. Study Selection: Inclusion criteria for studies included contrast between groups with delirium and without delirium; an objective continuous or binary measure of cognitive outcome; a final time point of 3 or more months after the delirium episode. The electronic search was conducted according to established methodologies and was executed on October 17, 2018. Data Extraction and Synthesis: Three authors extracted data on individual characteristics, study design, and outcome, followed by a second independent check on outcome measures. Effect sizes were calculated as Hedges g. If necessary, binary outcomes were also converted to g. Only a single effect size was calculated for each study. Main Outcomes and Measures: The planned main outcome was magnitude of cognitive decline in Hedges g effect size in delirium groups when contrasted with groups that did not experience delirium.