Survival study of vascular dementia in Rochester, Minnesota
Knopman DS, Rocca WA, Cha RH, Edland SD and Kokmen E;
Commented by , 24 Feb 2003
Aim of the study
To investigate the relationship between features and definition of vascular dementia (VaD) and survival.
Method
Systematic review of medical records from the Rochester Epidemiological Project to identify incident cases of dementia in Rochester from January 1, 1985 through December 31, 1989.
Dementia and Alzheimer disease (AD) were defined using the criteria of the 4th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV). VaD was defined by ad hoc criteria, including imaging: either dementia onset or worsening within three months of a clinical stroke, or bilateral gray matter infarctions.
Three sets of published diagnostic criteria for VaD were also applied to the analysis: DSM-IV criteria, National Institute of Neurological Disorders and Stroke-Association Internationale pour la Recherche et l’Enseignement en Neurosciences (NINCDS-AIREN) probable VaD criteria, International Classification of Diseases 10th revision (ICD-10) criteria.
Each patient with dementia was matched by age and gender to a referent person free of dementia, and all were followed from the onset of dementia (or index year) through death, censoring or the end of the study.
Results
Using 479 patients with incident dementia and 479 referent subjects, it was found that patients with VaD had worse mortality than referent subjects (relative risk [RR] 2.7; 95% confidence interval [CI] 1.9-3.9), patients with dementia all types (RR, 1.8; 95% CI 1.6-2.1), and patients with AD (RR, 1.4; 95% CI, 1.2-1.7).
The median survival was
- 3.3 years for patients with VaD versus 7.1 years for their referent subjects
- 5.2 years for patients with all types of dementia vs 7.5 years for their referent subjects
- 6.1 years for patients with probable AD vs 7.2 years for their reference subjects
Among patients with VaD, those with dementia temporally related to a stroke (as required in NINCDS-AIREN criteria for probable VaD) had the worse relative mortality (RR, 4.5; 95% CI, 2.7-7.4) compared to those with only imaging evidence of bilateral infarction in gray matter structures (RR, 2.4; 95% CI 1.5-3.8).
When the temporal relationship was not part of the VaD definition, as in the DSM-IV, survival was better. Men had a worse mortality than women.
Discussion
These results add to the emerging body of knowledge about vascular cognitive impairment, which includes all types of cognitive impairments associated with cerebrovascular disease.
Recent findings of improvement of cognition as measured by the Mini Mental State Examination and the Alzheimer Disease Assessment Scale using cholinesterase inhibitors such as galantamine and donepezil for patients with mixed AD/VaD and probable VaD have stimulated interest in the pharmacological symptomatic treatment of dementia associated with stroke.
Furthermore the overlapping vascular risk factors such as systolic hypertension between AD and VaD have led to systematic efforts at controlling vascular risk factors in both types of dementias.
This study adds useful information on the prognosis for survival of patients with VaD as defined by different set of diagnostic criteria, which may influence selection of cases for future clinical trials.
It adds to information from other recent studies looking at survival in AD (Brookmeyer et al, Archives of Neurology 2002; 59; 1764-1767), Parkinson’s disease (PD; Elbaz et al, Archives of Neurology 2003; 60; 91-96), PD with dementia (Levy et al, Neurology 2002; 59; 1708-1713). These data will be useful to assess in the near future if current pharmacological treatments for dementias are modifying survival.