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Affective Spectrum Disorders Current Issues
The Use of Rating Scales in Affective Disorders
a report by
Per Bech
Professor, Applied Psychometrics, University of Copenhagen
Since the paradigmatic change heralded by the release of the Diagnosis Using sophisticated software programs such as the Statistical Analysis
and Statistical Manual of Mental Disorders, Third Edition (DSM-III),
1
the System (SAS), the rating scale data can be analysed by the physicians
focus in our diagnostic systems for mental disorders has been on signs themselves. However, the sections of psychometrics in the SAS
9
designed to
and symptoms rather than aetiological factors, and has entailed a high help the physician evaluate the reliability and validity of rating scales refers
reliance on the symptom rating scales of psychopathology, especially in to a form of mathematical reasoning that may lead to a misuse of rating
the field of affective disorders. scale data. Thus, the reliability measure co-efficient alpha is recommended,
although Feinstein wrote its obituary two decades ago.
10
The factor validity
In the DSM-III (as well as in the DSM-IV
2
or the International Statistical of rating scales is also recommended in the SAS, although the SAS user is at
Classification of Diseases and Related Health Problems, 10th Revision the same time warned that factor analysis can be seductive in that it takes a
[ICD-10]
3
), the diagnosis of depression provides a global impression of large number of baffling variables and turns them into a clear-cut set of just
the severity of depressive states through their symptoms, e.g. minor a few factors.
9
In the following, the use of rating scales for affective
versus major depression or mild, moderate and severe depression. When disorders, as recommended by Feinstein
10
and Borsboom,
8
will be outlined.
Hamilton
4
developed his Hamilton Depression Rating Scale (HAM-D), he
made an attempt to characterise the global impression of depressive The Clinimetrics of Rating Scales
states by a total score of the 17 items in the scale (HAM-D
17
). Since then, In his monograph on clinimetrics, Feinstein
10
referred to three different
it has consistently been shown that the HAM-D can be used in all forms types of rating scale and their rational uses.
of depressive disorders.
5
As summarised by Paykel:
6
“…We all know the
appropriate meaning of a Hamilton score of 17, 13 or 26…”. Over The Apgar or Global Impression Type of Rating Scales
the last few decades, the HAM-D has been the scale most frequently used The Apgar scale was developed as a rating scale for the clinical condition
when measuring the outcome of antidepressive therapy. Rating scales for of a newborn baby.
11
It is probably one of the most commonly used
affective disorders have their major use as outcome scales, and this article scales in clinical medicine worldwide. It is a very short scale, containing
will review the correct use of the various scales for affective disorders in five items, each of which can be scored from zero to two. In other words,
this respect. the theoretical score range of the sum score is from zero to 10. A high
score indicates a better condition. As the five items are diverse (covering
The Mathematics of Rating Scales heart rate, muscular tone, respiration, colour and reflex response), the
Fifty years ago, when the antimanic effect of chlorpromazine or the total score gives only a rough global impression of the condition. An
antidepressive effect of imipramine were identified but were found to be Apgar score of five, for example, indicates that the baby’s condition is not
controversial by many psychiatrists, the conclusion was that when splendid. However, if we want to determine what is wrong with this
examining the effects of these new psychopharmacological drugs, the baby, we need to check the individual items. Therefore, a profile score is
physician lacked a system of statements from which the observed facts often needed as the total score is not sufficient. As pointed out by
could be derived by formal mathematical reasoning.
7
Mathematical Feinstein,
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the Apgar type of scale is not valid for measuring outcome of
reasoning is indeed the most reliable way to measure the mind.
8
a specific treatment.
The Hamilton or Factor-based Type of Rating Scales
Per Bech is a Professor of Applied Psychometrics at the
University of Copenhagen. Prior to this he was a Professor
The HAM-D
17
is a rating scale for assessment of the clinical condition of
of Clinical Psychiatry at Odense University and Head of the depressive states.
12
As mentioned above, Hamilton developed his scale to
Psychiatric Unit at Frederiksborg General Hospital. He was
measure depressive states globally, but not for the monitoring of changes
one of the founder members of the European College of
Neuropsychopharmacology (ECNP) in 1987, Past President
due to treatment effect. It is a rather large scale, containing at least 17 items,
of the Association of European Psychiatrists (AEP)
each of which can be scored either from zero to four or from zero to two,
(1992–1994) and Head of the Research Unit at the World
Health Organization (WHO) Centre for Psychometrics
with a theoretical score range of the sum score from zero to 52. A high score
(1985–2005). Professor Bech has published several books on applied psychometrics and indicates higher severity of depressive states. Feinstein
10
included the HAM-
approximately 400 papers in the field of psychometrics, clinical psychiatry and
D
psychopharmacology. He received his MD from the University of Copenhagen in 1969, and in
17
in his monograph to illustrate a scale that has been ‘produced’ by factor
1972 he received the Gold Medal in Psychiatry for studies of the dose–response effect of
analysis.
12
Like the Apgar scale, the HAM-D contains diverse symptoms of
cannabis on psychological tests at the University of Aarhus. He specialised in clinical
depressive states and the total score is therefore only a global impression of
psychiatry 1978, and in 1981 he obtained his DScM for rating scales of affective disorder.
the severity of depression. A score of 18 indicates a severity of depressive
E:
pebe@noh.regionh.dk
state as seen in major depression and a score of seven indicates remission.
However, the total score is not a sufficient statistic for measuring the specific
14 © TOUCH BRIEFINGS 2008
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