Bech.qxp 30/6/08 02:15 Page 16
Affective Spectrum Disorders Current Issues
Table 4: Psychometric Description of Interview-based Rating Table 5: Standardisation of Rating Scales for Affective Disorders
Scales for Affective Disorders
Symptom Rating Scales CGI Minimum CGI Moderate
Scales
(two or fewer) (four or more)
(Pearsons/Interclass)
Remission Relapse
Classic Modern
HAM-D
17
718
Co-efficients Internal Consistency Item Response Models
HAM-D
6
49
Co-efficient Alpha
MES 6 15
Co-efficient of Rasch Analysis
MADRS 12 25
Homogeneity Acceptance
MAS 6 15
YMRS 8 20
HAM-D
17
0.48–0.97 0.46–0.91 0.19–0.27 –
Standardisation of rating scale for affective disorders
19,44
with reference to the Cinical Global
HAM-D
6
0.78–0.96 0.67–0.80 0.40–0.44 + Impression Scale (CGI-S).
13
HAM-D17 = 17-item Hamilton Depression Rating Scale;
MES 0.75–0.93 0.91 0.49 +
HAM-D6 = Six-item Hamilton Depression Rating Scale; MES = Bech-Rafaelsen Melancholia
Scale; MADRS = Montgomery–Asberg Depression Rating Scale ; MAS = Bech–Rafaelsen Mania
MADRS 0.65–0.97 0.90 0.43–0.46 –
Assessment Scale; YMRS = Young Mania Rating Scale.
MAS 0.80–0.99 0.88 0.40 +
YMRS 0.36–0.95 0.84 0.24 ?
Psychometric description by reliability and validity (classical and modern) of the most used
(Bech–Rafaelsen Mania Assessment Scale [MAS] and Young Mania Rating
interview-based rating scales for affective disorders.
19,43–46
HAM-D17 = 17-item Hamilton
Scale [YMRS]).
19,20
Table 4 shows the inter-rater reliability and validity of
Depression Rating Scale; HAM-D6 = Six-item Hamilton Depression Rating Scale; MES = Bech-
Rafaelsen Melancholia Scale; MADRS = Montgomery–Asberg Depression Rating Scale; the scales shown in Tables 2 and 3. For all the scales the reliability
MAS = Bech–Rafaelsen Mania Assessment Scale; YMRS = Young Mania Rating Scale.
co-efficients are of statistical significance, although most problems have
emerged with the YMRS.
21
The Guttman scale model is a deterministic version of the item response
theory models, of which the Rasch analysis is a parametric version and the As most investigators still show the classic co-efficient alpha for testing
Mokken analysis a non-parametric version.
8
Thus, statistical probability has of internal consistency, this co-efficient is included in Table 4. However,
been taken into account in the Rasch and Mokken models. this is not a test of unidimensionality, nor is factor analysis a test for
unidimensionality. Thus, for the testing of the psychometric validity of
According to Feinstein
10
and Borsboom,
8
the clinical (face) validity of bipolar depression, item response theory models have to be used.
22
rating scales is a non-statistical problem. Thus, as stated by Guttman,
16
the face validity of items to be included in a rating scale is the extent The Measure of Response to Treatment in
to which they belong to the universe of items accepted by experienced Patients with Affective Disorders
clinicians (clinical validity). The scale function tested by the item The most conservative measure of response to treatment in patients with
response theory analysis is the unidimensional meaning of ‘more’ or affective disorders in the acute treatment phase is a 50% reduction or
‘less’, which is meaningful only for scales when the total score is a more of the baseline total score at end-point (typically after six to eight
sufficient statistic. The first depression rating scale designed according to weeks with antidepressants and after two to four weeks with
the Guttman type of scale for measuring changes in depressive states antimanics). This corresponds with the ‘much improved’ or ‘very much
during antidepressive treatment was the Cronholm–Ottosson Depression improved’ of the Clinical Global Impression Scale (CGI-S).
13
Scale.
17
The Bech–Rafaelsen Melancholia Scale (MES) was developed with
reference to this scale and the HAM-D.
17
In dose–response relationship trials of antidepressants, the effect size
statistic has been found to be the most sensitive response measure when
comparing experimental drugs with placebo.
23–25
In these trials it was
shown that the HAM-D
6
and MADRS
6
were more similar than HAM-D
17
The use of rating scales is of special
or MADRS
10
in showing a dose–response relationship. Even when
interest when assessing response to
analysing each single item within the HAM-D
17
for its sensitivity to
measure change (experimental drug versus placebo), the HAM-D
6
items
treatment (e.g. in dose–response
were found to be the most valid.
26
An effect size of 0.40 or higher when
studies) or to identify remission.
comparing the experimental drug with placebo was shown to be a
clinically significant response.
25
It has been demonstrated that an effect
size of 0.40 equals a number needed to treat (NNT) of 4.5.
27
Rating Scales for Measuring Outcome of Treatment in In trials with antimanics it is not possible to include placebo for ethical
Patients with Affective Disorders reasons. In such trials, the plasma level of the experimental drug in relation
Table 2 shows a scoring sheet with the three most important to the clinical effect by total rating scale score seems most convincing. In
clinician-rated scales for the measurement of symptom change during fixed-dose trials using plasma level at end-point, a negative correlation
antidepressive treatment. All three scales (the HAM-D
17
, MES and co-efficient will express the clinical relation so that higher plasma levels are
Montgomery-Asberg Depression Rating Scale [MADRS]) were developed associated with lower rating scale scores.
19
It has been shown that a
before the introduction of the DSM-III in 1980.
18
Table 3 shows the range significant negative correlation between the rating scale score and plasma
of symptoms in the two most frequently used clinician-rated scales for the level of olanzapine after two weeks of therapy with a fixed dose of
measurement of symptom change during treatment with antimanic 20mg/day emerged in manic patients using the MAS but not using the
drugs. They were also developed before the introduction of the DSM-III YMRS.
28
When using rating scales for affective disorders to express a
16 EUROPEAN PSYCHIATRIC REVIEW
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