comparison of clinical performance of aqt-cf, mmse, and adas-cog: preliminary results niels peter...
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Comparison of Clinical Performance of AQT-CF, MMSE, and ADAS-cog:
Preliminary ResultsNiels Peter Nielsen, M.D.
Siegbert Warkentin, Ph.D.
James Jacobson, M.D.
Lennart Minthon, M.D., Ph.D.
Elisabeth H. Wiig, Ph.D.
Copyright 2002 @ RAN Diagnostics, Inc.
Objectives
1. Compare the diagnostic utility of three measures of cognition (AQT-CF, MMSE, and ADAS-cog), used alone, for differentiating patients with Alzheimer’s Disease from normal patients.
2. Determine if a combination of tests provides better diagnostic utility than a single test.
3. Suggest a testing strategy for clinical application of these cognitive measures.
Sample Population
Normal AD P valuen 46 33
Language Swedish Swedish
Education > 11 yrs > 11 yrs
Age 70.85+/- 8.94
75.3 +/- 7.04 P<0.02
Cognitive Measures
AQT MMSE ADASProbe Temporo-
parietal dysfunction
Cognitive impairment
Comprehensive testing for AD
Test Color-form naming
Measure Time (sec) Point score Behavior rating
Normal < 60 27-30 <10
AD >70 <27 10 - 70
Test time 3-5 min 10 min 45 min
General Results
Normal AD P ValueAQT-CF 51.21+/- 9.17 96.88 +/-
21.78< 0.001
MMSE 29.07 +/- 1.44
23.03 +/- 3.64
< 0.001
ADAS-cog 7.4 +/- 3.51 23.38 +/- 9.14
< 0.001
Sensitivity Analysis
Sensitivity
(%)
Specificity
(%)
Predictive Value
(%)
AQT-CF 88 100 95
MMSE 82 94 87
ADAS-cog
95 98 97
Receiver Operator Curve
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
f alse alarm
aqt-cf
random
mmse
adas-cog
False Alarm
Diagnosis
Stepwise Discriminant Analysis
Y(0,1) = B0 + B1X1 + B2X2 +B3X3 …+BiXi
Variables = age, gender, AQT-CF, MMSE, ADAS-cog
Y(0,1) = -3.720 + .122(ADAS-cog) + .030(AQT-CF)
Best discrimination by ADAS-cog & AQT-CF
AGE, gender, MMSE not included
Sensitivity Analysis:AQT-CF and ADAS-cog
Normal
AD
Normal
21 0 Spec= 100%
AD 1 44 Sens= 98%
Predicted
Actual
AQT-CF and ADAS-cog: Predictive Value = 98.5%
Measure CharacteristicsAQT-CF MMSE ADAS-
cogTime 3-5 min 10 min 45 min
Monitor Nonmedical
Professional
Professional
Cost Low Moderate High
Conflicts Factors
None Age, education, culture, literacy
Judgment, experience
PV(alone/ combo)
95/98.5 87/NA 97/98.5
Screening Yes Yes No
Diagnosis Yes Yes
Summary
1. Used alone, AQT-CF and ADAS-cog have comparable predictive value, superior to MMSE.
2. Used in combination, the best PV value is obtained by using AQT-CF and ADAS-cog.
3. For screening, AQT-CF is preferred because of short test time, independence from a medical professional, and high predictive value.
4. For final diagnosis, the combination of AQT-CF and ADAS-cog provides the highest predictive value.
Conclusions
1. AQT-CF is a powerful clinical tool to assess cognitive functions associated with temporo-parietal activation.
2. Test characteristics of AQT-CF make it especially valuable as an initial screening test for both normal individuals and suspected AD patients.
3. For final diagnosis, the best predictive value is provided by use of both the AQT-CF and ADAS-cog.