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The largest changes in diagnostic categories between the standard and the comprehensive diagnostic process was a 9%decrease in the diagnosis of Alzheimer's disease,a 6%increase in the diagnosis of mixed dementia(due largely to laboratory studies),and a 4%increase in the diagnosis of vascular dementia(due to neuroimaging).The clinical indicators were 82% sensitive and 50%specific in predicting that neuroimaging studies would change the diagnosis.In six cases,meaningful neuroimaging findings were not associated with any clinical indicator(5%false negatives).In 43 cases, neuroimaging provided no significant clinical findings despite the presence of an indicator(36%false positives).In this convenience sample, diagnostic accuracy was improved to a comparable degree by laboratory and neuroimaging studies,although at a significant difference in cost.Use of the four clinical indicators would have reduced the frequency of neuroimaging studies by 33%but missed clinically meaningful information in 5%.Although imperfect,the Practice Parameters represent a first stem towards improving the cost effectiveness of the dementia work-up. |
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