H. Chui et Q. Zhang, EVALUATION OF DEMENTIA - A SYSTEMATIC STUDY OF THE USEFULNESS OF THE AMERICAN-ACADEMY-OF-NEUROLOGY PRACTICE PARAMETERS, Neurology, 49(4), 1997, pp. 925-935
Objective. This study examined the usefulness of the ''Practice Parame
ters for the Evaluation of Dementia,'' published by the Quality Standa
rds Subcommittee of the American Academy of Neurology (1994). The Prac
tice Parameters are stratified according to three levels of certainty
(standards, guidelines, and options), and suggest indications for the
use of neuroimaging studies. Methods. We reviewed 119 consecutive case
s referred for assessment of memory loss to a university-affiliated in
terdisciplinary clinic. We assessed the diagnostic value of laboratory
, neuropsychological, and neuroimaging studies above the standard hist
ory, neurologic, and mental status examinations. We also assessed the
sensitivity and specificity of four clinical indicators (i.e., early s
ymptom onset, noninsidious course, focal neurologic signs or symptoms,
and gait disturbance) for predicting the diagnostic utility of neuroi
maging studies. Results. 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 th
e diagnosis of mixed dementia (due largely to laboratory studies), and
a 4% increase in the diagnosis of vascular dementia (due to neuroimag
ing). The clinical indicators were 82% sensitive and 50% specific in p
redicting 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 pro
vided no significant clinical findings despite the presence of an indi
cator (36% false positives). Conclusions. 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 infor
mation in 5%. Although imperfect, the Practice Parameters represent a
first step toward improving the cost effectiveness of the dementia wor
k-up.