Reliability and Validity of the DSM

Keller et al
1. Keller investigated the reliability of the DSM. Keller found that: Inter-rater reliability was fair to good, whilst test-retest reliability was fair at best.
2. Zanarini et al
  1. Zanarini came to very similar conclusions to Keller. Zanarini found an inter-rater reliability correlation of 0.8, and a test retest correlation of only 0.6, There was only one week between diagnostic sessions.
3. Keller conducted a multisite study into the DSM classification of major depressive disorder and dysthymia. 524 depressed individuals from inpatient, outpatient and community settings from 5 different sites. Each person was assessed using the DSM criteria twice with 6 months in between each. Results found inter-rater reliability across the sites was 'fair to good' whilst test retest reliability was fair for dysthymia, and 'poor' for major depressive disorder.
Beck et al
1. Beck, and 3 other psychologists set out to investigate the reliability of the DSM. 153 patients were seen by at least two of the psychologists, and were given a diagnosis.Each psychologist had previously agreed on the DSM. However an agreement level of only 54% was reached.
2. The Beck Depression Inventory
  1. Test-reliability of the BDI was measured by Beck et al. He he used the responses of 26 outpatients tested at two therapy sessions one week apart. A correlation of 0.93 was found for test-retest reliability.
    1. This study was conducted by Beck himself, which means there is a large chance of researcher bias, as he created the BDI.
  2. Visser et al investigated 92 patients with Parkinson's Disease for depression using the DSM and the BDI. In the second part of the study, 60 patients completed the BDI for a second time and a test-retest correlation of 0.88 was found. This suggest that the BDI was a reliable measure of depression.
Reasons for the low reliability of the DSM. (Suggested by Keller)
1. A minimum of 5 out of 9 symptoms are required in order to be diagnosed with major depressive disorder. In this case, patients who suffer on the threshold of being diagnosed, may be diagnosed with another condition. Small differences in opinion may lead to the patient being diagnosed with the 5th symptom, or not.
2. Unclear criteria and a lack of specificity.
  1. This accounted for 62.5% of disagreements between Beck and his colleagues.
3. Inconsistencies in the information presented by the patient.
4. Inconsistencies in techniques used by clinicians, such as interviewer technique.
Further Issues Affecting Reliability of Diagnosis
1. Despite comprising of years worth of research and evidence, there is still some unclear areas of the DSM. For example, in terms of distinguishing between different subtypes of depression, there is still much disagreement between clinicians.
2. Due to the lack of a clear, standardised objective diagnostic system to diagnose depression, there is often some difficulty in diagnosis. For example, patients may display all the clear signs of depression in their body language; however some patients may do their best to conceal their depression by trying to portray positive body language. This makes clean cut diagnosis very difficult. Making it difficult for clinicians to make reliable diagnosis.
Are there several distinct types of depression?
1. McCullough et al - compared 681 outpatients with varying types of depression (for example dysthymia and major depressive disorder). Results found that there was a considerable overlap in the symptoms, responses to treatment and various other variables. This made it hard to fully justify different subtypes of depression.
Are GP's diagnosis valid?
1. Van Weel-Baumagarten suggested that GP's diagnosis of depressed patients may not be as objective as one made by a secondary care specialist. This is due to the GP having pre-existing knowledge of the patient. That knowledge may influence them into making a decision based on what they already know, and not the presenting symptoms.
The Beck Depression Inventory
1. Content validity - The BDI has high content validity, as it was constructed as a result of consensus among clinicians concerning symptoms found among psychiatric patients.
2. Concurrent validity is high, as Beck himself found between itself and the Hamilton Depression Scale.
3. Construct validity is high in the BDI, as studies have shown that there is a correlation between BDI scores and symptoms such as anxiety, loneliness and disturbed sleep patterns.
Cultural Differences in the Diagnosis of Depression
1. It has been noted, that ethnic minority groups within the UK, are far less likely to seek profession help for depression compared to white people.
2. There are multiple explanations as to why ethnic minority groups display such a stigma towards mental illness. One explanations is that people in ethnic minority groups, often see depression as a social problem, or an emotional reaction to a situation. However people within the middle-class white group, often see depression in a biological perspective. Suggesting that it does it proper treatment.
3. Karasz
  1. Karasz conducted a study into this phenomenon. He gathered 36 South Asian immigrants, and 37 European Americans. He gave each person a vignette describing symptoms. The South-Asian group described the problem in social and moral terms. The South-Asian group emphasised self management and unprofessional help in terms of treatment. However, in contrast the European American group addressed the problem in biological terms emphasising causes such as hormonal imbalance and/or neurological problems.
Further Issues Affecting Validity
1. It is argued that treating depression as a disease, in many aspects is not a valid thing to do. This is due to many clinicians believing that depression is a normal human reaction to situations and to label it as a disease only potentially worsens the situation.
2. Depression rates are twice as high in women than they are men. However, this is a social difference, as it is often seen more 'socially acceptable' for a woman to go to a GP and talk about her mental health than it would be a man.
3. Socio-cultural background is important in the diagnosis of depression. It is often that clinicians from the majority population will misinterpret certain behaviours that are displayed by the minority group resulting in misdiagnosis. Therefore it is important that clinicians are able to interpret different behaviours from varying cultures.
The Stigma of Mental Illness
1. The DSM and the ICD are classification systems that are used worldwide. However there are several countries that have not adopted the use of these manuals, for example China. In China, they protest against how the western diagnosis systems separate body and mind. In the Chinese Classification of Mental Disorders manual, there is a neurasthenia category. The core symptoms of this category are identified as mental and/or physical fatigue. Due to the stigma in many Asian cultures that means admitting mental illness is a great sign of weakness, this category allows for a form of proper diagnosis without any psychiatric labels.

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Reliability and Validity of the DSM

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	Created by Tom Gough over 9 years ago