Risk of a Diagnosis of Dementia for Elderly Medicare Beneficiaries after Intensive Care.
Academic Article
Overview
abstract
BACKGROUND: Critical illness is likely associated with an increased risk of dementia, but the magnitude remains uncertain. METHODS: The cohort was a random 2.5% sample of Medicare beneficiaries who received intensive care in 2005 and survived to hospital discharge. Patients were matched with general population controls (age, sex, and race) with 3 yr of follow-up. The authors used an extended Cox model to assess the risk of a diagnosis of dementia, adjusting for the known risk factors for dementia, and the competing risk of death. RESULTS: Among 10,348 intensive care patients who survived to hospital discharge, dementia was newly diagnosed in 1,648 (15.0%) over the 3 yr of follow-up versus 12.2% in controls (incidence per 1,000 person-years, 73.6; 95% CI, 70.0 to 77.1 vs. 45.8; 95% CI, 43.2 to 48.3; hazard ratio [HR], 1.61; 95% CI, 1.50 to 1.74; P < 0.001). After accounting for the known risk factors in the year before the index hospitalization, the risk of receiving a diagnosis of dementia remained increased in patients who received intensive care (adjusted HR, 1.43; 95% CI, 1.32 to 1.54; P < 0.001). Inclusion of identifiable risk factors accrued during the quarter of critical illness accounted for almost all of the increased risks (adjusted HR, 1.09; 95% CI, 1.00 to 1.20; P = 0.06). CONCLUSIONS: Elderly critical care survivors have a 60% increased relative risk, but only 3% increased absolute risk, of receiving a diagnosis of dementia in the subsequent 3 yr compared with the general population. This increased risk is not accounted for by risk factors preexisting the critical illness. Surveillance bias, which increases the likelihood of receiving a diagnosis of dementia, could account for some or all of these additional risks.
