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Archives of Clinical
Neuropsychology 2009 24(8):721-728
High Specificity of the
Medical Symptom Validity Test in
Patients with Very
Severe Memory Impairment
Ankush Singhala,
Paul Greenb,*, Kunle
Ashayea, Kuttalingam Shankara
and David Gilla
a
Department of Psychiatry, Lister
Hospital,
Stevenage,
UK
b Private Practice in Clinical
Neuropsychology, Edmonton, Alberta, Canada
The above paper is now available online to NAN
members.
Q) Why does it matter that analysis of the MSVT and
NV-MSVT profiles very rarely misclassifies advanced
dementia patients as poor effort?
A) Because these are the most cognitively impaired
people we can test. False positives on an SVT occur if
someone tries their best and actually cannot pass.
Advanced dementia patients are more likely than anyone
else to be false positives on SVTs. If they very rarely
produce false positives, it is not plausible that people
with lesser impairment will be false
positives (e.g. Mild TBI adults).
Note: In this approach ‘false positive’ does not
refer to being wrongly classified as a malingerer. It
means that the results indicate poor effort and
unreliable test data, when the data are actually valid
and a result of best effort. This is an important
distinction. It is not advisable to say that a poor
effort profile on MSVT or NV-MSVT means the person is
malingering. We should be meticulous and not infringe on
the right of judge and jury to decide intent. It is more
conservative and scientifically valid to conclude that
results appear reliable or that they appear unreliable due to poor effort.
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On page 456 of the Archives of Clinical Neuropsychology
conference abstracts (vol 24, issue 5, August 2009),
there is a study by Davis, Ramos, Sherer, Bertram and Wall
(2009).
They looked at the
sensitivity of the
TOMM and WMT to malingering in two groups, who were naive or
coached simulators.
- Sensitivity for the TOMM was a mean of
48% (59% for naive
and 38% for coached simulators).
- Sensitivity for the WMT was
71% for both naive
and coached simulators.
- Both the TOMM and WMT had 100%
specificity in a control group making a good effort (using
only pass/fail easy subtests).
Conclusion:
The WMT was more sensitive to poor effort than the TOMM,
especially in simulators who had been coached.
They were
equally specific in controls.
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On page 487 of the Archives of Clinical
Neuropsychology conference abstracts (vol 24, issue
5, August, 2009), there is a study of the relative
sensitivity and specificity of embedded effort measures
versus stand alone SVTs like the TOMM, Rey-15, VSVT and WMT. The authors are Miele, Lynch and McCaffrey (2009)
Conclusion:
In litigating patients, the data on embedded symptom
validity indices do not support their use at the
exclusion of
free standing SVTs.
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William A.
Lindstrom, Jr., Jennifer H. Lindstrom, Chris Coleman,
Jason Nelson & Noel Gregg. The Diagnostic
Accuracy of Symptom Validity Tests when Used with
Postsecondary Students with Learning Disabilities: A
Preliminary Investigation.
Archives of
Clinical
Neuropsychology in press but available online (October
2009)
Conclusion:
This independent study shows that the WMT
is more sensitive to poor effort than the TOMM in people
asked to simulate impairment.
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1) In the following study by
Booksh et al., the WMT performs better than clinical judgment in
classifying students asked to simulate ADHD;
2) Poor effort has a greater effect on Connors' CPT than
does ADHD;
3) Clinical judgment has high false positive rate, whereas
WMT has a zero false positive rate;
4) the Fifteen Item Test displays zero sensitivity (It is
impossible to get worse sensitivity than that!).
Booksh, R., Pella, R., Singh &
Gouvier, W. (in press) Ability of College Students to Simulate
ADHD on Objective Measures of Attention. Journal of Attention
Disorders.
For pre-print, email
wgouvie@lsu.edu
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Brigham Young University
researchers offer strong support for the WMT as a combined test
of effort and verbal memory:
Three cases described as having
bilateral hippocampal damage and amnesia all passed the
easy subtests of the WMT.
However, they all had profound
impairment of verbal memory on the WMT memory subtests.
See this abstract:-
DISCUSSIONS/WMT_in_bilateral_hippocampal_lesions_&_amnesia.doc
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Children with severe TBI
easily pass but adults with mild TBI fail: How can that be?
Carone, D. Children with moderate/severe brain
damage/dysfunction outperform adults with mild to no brain
damage on the Medical Symptom Validity Test. Brain Injury, 2008;
22, 12, 960-971. |
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Low
false positive rate on MSVT in dementia because of profile analysis.
Note that MSVT data do not just yield 'pass' or 'fail' but that there is a specific "dementia profile", which is unlike that from simulators.
Also see "Result Interpretation" on the bar at the left on this
web page.
Characterization of the Medical Symptom Validity
Test in evaluation of clinically referred memory
disorders clinic patients
Laura L.S. Howe,
Ashton M. Anderson,
David A.S. Kaufman,
Bonnie C. Sachs and
David W. Loring
Available online 24 July 2007.
Abstract
We prospectively evaluated performance of 63
referrals to a memory disorders clinic who
received the Medical Symptom Validity Test (MSVT)
as part of their standard neuropsychological
evaluation. The patients were grouped based on
independent medical diagnoses and presence or
absence of a potential financial incentive to
under-perform. Twenty-seven patients (42.9%)
scored below cutoffs on the MSVT symptom
validity indices. Two individuals in the
potential financial incentive group showed clear
signs of invalid responding (18.2%). Twenty-two
of the remaining 25 patients who failed the
symptom validity indices corresponded to the
dementia profile. Three individuals did not
correspond to the dementia profile but are
thought to have performed validly representing a
4.8% false positive rate. When considering all
MSVT indices, the base rate of invalid
responding in the potential financial incentive
to under-perform group increased to 27.3%.
Combining all groups our base rate of invalid
responding was 4.8%. Specific performances are
presented.
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DO YOU USE THE FBS & RBS
together?
If so, see Roger Gervais, P. Lees-Haley & Y. Ben Porath's poster on jointly using FBS and RBS to get better prediction of cognitive symptom exaggeration. For the poster click links.
2007 handout GERVAIS
2007 poster NAN GERVAIS
NAN 2007 Handout
NAN 2007 Handout
In the graph, bars show percent failing SVTs. Bar 2 is "High FBS/Low RBS" and bar 4 is"High FBS/High RBS". Note the difference in SVT failures in these two groups. The first group is "Low FBS/Low RBS" and the fourth group is "High FBS/High RBS".
