Mortality Of Older Patients With Dementia After Surgery For Chronic Subdural Hematoma: A Nationwide Study

Background: dementia is associated with an excess risk of death but mortality after chronic subdural hematoma (CSDH) evacuation in older people with dementia is unknown. We assessed the association between dementia and 1-year case-fatality in older persons undergoing CSDH evacuation.Methods: we conducted a nationwide Finnish cohort study including all older persons (>= 60 years) undergoing CSDH evacuation during 1997-2014 (referred to as cases). We identified controls, without a diagnosis of CSDH, that were matched for age, sex and year of first hospitalisation with a new dementia diagnosis. We identified cases and controls with a pre-existing diagnosis of dementia. Outcome was 12-month mortality. Mortality was compared in case-only and case-control analyses.Results: of 7,621 included cases, 885 (12%) had a pre-existing diagnosis of dementia. The proportion of cases increased from 9.7% in 1997-2002 to 12.2% in 2012-2014 (P = 0.038 for trend). In the case-analysis, dementia independently associated with 1-year case-fatality (dementia vs. no dementia odds ratio [OR] 1.50, 95% confidence interval [CI] 1.26-1.78). Sensitivity analysis suggested the association to be strongest for those 60-69 years old (OR 3.21, 95% CI 1.59-6.47). In the case-control matched analysis, 1-year mortality was 26% in the dementia CSDH surgery group compared to 16% in the dementia non-CSDH controls (P < 0.001).Conclusion: dementia is a significant risk factor for 1-year mortality after CSDH surgery in older people. The proportion of older CSDH patients having a pre-existing diagnosis of dementia is increasing. Thus, there is a need for improved evidence regarding the indications and benefits of CSDH evacuation among older persons.