Download Issues Surrounding the Diagnosis and Classification of Depression

Issues Surrounding the Diagnosis and Classification of
Depression
There are a number of issues surrounding the diagnosis and classification of depression.
One of the main reasons for this is that there is no objective test for depression or other
mental disorders.
Issue 1: Reliability of Classification and Diagnosis
Reliability refers to how far the classification system produces the same diagnosis for a
particular set of symptoms.
 In order for a classification system different clinicians should reach the same diagnosis
when assessing the same individual (inter-rater reliability)
 Also, the test should produce the same results for the same individual on two separate
occasions (test-retest reliability)
1. Beck (1961) looked at inter-rate reliability and found that it is actually quite low at 54%,
meaning their diagnosis only agreed with each other for 54% of the 154 individuals.
 Beck noted that in 154 cases the patients gave different information to the two
health professionals.
2. Keller et al. (1995) carried out a multi-site study designed to explore the reliability of the
DSM-IV classification system for major depressive disorder and dysthymia. They
recruited 524 depressed individuals and each was interviewed using the DSM criteria
and then interviewed again 6 months later to establish a measure of test-retest
reliability. Results showed that inter-rater reliability across the different sites where the
patients were recruited from was ‘fair to good’, but test-retest reliability was ‘fair’.
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Keller suggested that the DSM diagnosis may have lacked reliability because for
a diagnosis of major depressive disorder to be made, a minimum of 5 out of 9
symptoms must be present.
If the presence of a particular symptom is quite subtle, a one item disagreement
(e.g. considering that an individual is sufficiently lethargic that it satisfies the
symptom of ‘shift in activity levels’) makes the differences between a diagnosis
of MDD or a less serious illness.
3. Similar was found for Zanarini et al. (2000) who found an inter-rater reliability correlation
of 0.80 for MDD and a test-retest correlation of just 0.61 with one week between
diagnosis sessions.
These studies clearly highlight that there is room for subjective interpretation on the part of
the person diagnosing depression.
Meehl (1977) suggests that mental health professionals should be able to count on the
total reliability of the diagnostic tools they have at their disposal if they:
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Pay close attention to medical records
Are serious about the process of diagnosis
Took account of the very thorough descriptions presented by the major classificatory
systems.
Considered all the evidence presented to them.
However, this is better in theory than in practice. Because...
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Health professionals will be relying on retrospective data, given by a person whose
ability to recall much relevant information is unpredictable (or may be exaggerating
the truth or lying!)
There is limited time and resources (which is especially relevant in today’s economic
climate)
Many professionals are rushed and preoccupied, especially since today’s health
system has the aim of seeing as many patients as possible.
Issue 2: Validity of Classification and Diagnosis
Validity refers whether the classification system is actually measuring what it aims to
measure.
 Descriptive validity = how similar individuals diagnosed with the disorder are
 Predictive validity = whether the diagnosis is able to predict the course and
outcome of the disorder and also the right treatment.
Some commentators have highlighted the extent to which many disorders described in
the diagnostic manuals actually overlap. There seems to be a growing trend in clinical
psychology to diagnose patients as suffering from ‘co-morbid’ disorders (i.e. disorders that
often seem to occur together).
Instead of acknowledging that the methods by which diagnostic decisions are arrived at
are lacking validity, clinicians diagnose two separate disorders.
Kessler et al. (1996) found that the chances of someone with a form of MDD suffering from
any other disorder is 74% and suffering from an anxiety disorder is 58%.
Are GP diagnoses valid?
For most people, a diagnosis of depression is given by their local GP. GPs specialise in
general medicine and it has been suggested that about 50% of people who are showing
depressive symptoms when they go to see their GP are not diagnosed with depression.
Also, GPs are less objective because they base their classification on previous knowledge
of the patient rather than the actual presenting symptoms.
Rosenhan (1973) – Being Sane in Insane Places
Conducted a classical study that questioned the validity of the diagnosis of metnal
disorders. He believed that psychiatrists couldn’t tell the difference between sane people
and people with mental disorders.
 People who didn’t have any kind of metnal health problem got themselves admitted
into a psychiatric unit by claiming that they heard voices – they became pseudo
patients.
 Once they’ve been admitted, they behaved ‘normally’.
 However, their behaviour was still seen as a symptom of their disorder by staff in the
unit. For example, one pseudopatient wrote in a diary and was recorded as displaying
‘writing behaviour’.
This questions the validity of the diagnosis of mental disorders – once people are labelled
as having a disorder, all of their behaviour can be interpreted as being caused by the
disorder.
However, note there were flaws in this study and it was conducted more than 30 years
ago when diagnostic practice was very different.
N.B. When talking about this you must make it relevant to depression
Issue 3: Culture Bias
The study of classification and diagnosis is an area that can be criticised as culturally
biased. It is assumed that systems such as the DSM and ICD developed in the West, apply
across all cultures. Content and scoring procedures reflect the culture of white Europeans
and so may not accurately assess people from other cultures.
For example, psychiatrists in countries such as Pakistan, India and China think classification
systems that are developed in the west place too much emphasis on separating mind
and body.
Culture bias may cause psychiatrists to overestimate or underestimate psychological
problems in members of other cultures.
Issue 4: Gender Bias
It has been found that rates of major depression are about twice as high in females as in
males and this finding holds good across cultures. Some people have suggested that this is
a misleading statistic and reflects diagnostic practice rather than real fender differences.
For example, it is ‘more acceptable’ for women to admit to the kinds of symptoms that
characterise depression than men.
Winter believes that one explanation for this difference is that ‘general practitioners and
psychiatrists, who are predominately white, middle class and male, may be biased
against, or insufficiently sensitive to cultural and social situations of black, working class or
female patients’.
Issue 5: Labelling
There is huge debate surrounding the issue of ‘labelling’ since it can be stigmatising and
lead to a self-fulfilling prophecy. People think in terms of the label and not the person and
it can lead to social isolation, distress and difficulty in employment.
How valid is it to call depression a disease? Some people argue that sad and depressed
moods are normal reactions to problems of living and that it is wrong to classify depression
as an illness and stick a disease label on an individual.
The counter argument is that depression can be extremely distressing for the individual
and can lead to very severe consequences, e.g. suicide. Accurate diagnosis leads to
appropriate treatment and relief for the person experiencing the symptoms.
QUESTIONS
1. What is the difference between reliability and validity?
2. What is the difference between inter-rater and test-retest reliability?
3. How does Rosenhan’s (1973) ‘Being sane in insane places’ demonstrate that reliability is
clearly an issue when diagnosing mental illness?
4. What can be concluded from Keller et al’s study?
5. Why does Keller suggest that the DSM lacks reliability?
6. A diagnostic tool i.e. DSM should be objective. What does this mean and why is it
important?
7. What are predictive and descriptive validity?
8. What does Winter view as the reason why diagnosis can be culture and gender bias?