Discuss issues surrounding the classification and diagnosis of depression (24 marks)
A key concern regarding the diagnosis of depression is the reliability of the diagnosis; reliability refers to the consistency of a test or results. In order to increase the reliability of this, the test-retest method can be used to assess consistency. Within this, a patient is tested for depression twice over a period of time in order to establish whether or not the scores on the classification measure stay consistent; this would show a high concordance rate between test results. A strength of using the test retest method is that, if results have a low concordance rate from the two tests, it signposts that the patient is either getting better or worse in terms of their depression as their results have changed. For example, if a patient’s depression score decreases over time, it could signal to the psychiatrist that the treatment is working, and vice versa, if scores increase it can indicate that treatment is not working or the patient’s depression is getting worse, which tells them that they may need to make changes to help the patient. However, the problem with this is that some assessments have been shown to not consistently have good test-retest ability; predominantly this is the DSM-IV. This statement has been supported by research. For instance, Keller et al (1995) assessed 524 people with depression from inpatient, outpatient and community settings at 5 different sites. Within the study, each patient was interviewed by Keller using the DSM criteria at one point, and then interviewed again after 6 months, in order to distinguish a measure of the test-retest reliability. In regards to the reliability, they found that for the test-retest it was ‘fair’ or dysthymia and ‘poor to fair’ for major depression. Therefore, this study suggests that the DSM has an issue with the reliability of the test-retest method for classifying major depression. In order to improve the reliability, filming the behaviour of the patients can be done in order for the clinicians can practice their categorisation of depression, as this may improve the reliability of their diagnosis. However, evidence has also challenged the inter-rater reliability, and raised a concern with the reliability of diagnosing depression.
Another way in which the reliability of diagnosis can be measured is by checking the inter-rater reliability through seeing whether two or more independent researchers offer compatible depression scores. Idyllically, the DSM and other diagnostic tools would have a high concordance rate between the assessors in order for it to be highly reliable. Within Keller et al.’s study which investigated the reliability of the DSM, they established that the inter-rater reliability was ‘fair to good’. This suggests that this method is more effective than the test-retest method alone as the reliability is at a higher level, meaning the results can be trusted more if more than one professional agrees on them. Although, it is important to highlight that the reliability of this is still not completely consistent and trustworthy, meaning there is the risk of misdiagnosis still. This is a significant issue, as there is an implication of diagnosing someone incorrectly with depression because of the subjectivity of the classification, and this means that in the real world people will be labelled, and due to the negative associations people have with depression, it may make a mild depression more severe for a patient, therefore increasing the problem. From this, it is clear that an accurate classification and diagnosis for depression is important.
Likewise, measures must be reliable if they are to be valid. The person who carries out the diagnosis is important concerning the validity of a diagnosis. For most people, a diagnosis of depression is given by their local GP rather than a psychologist/psychiatrist, which may affect the validity of their diagnosis. GP’s are untrained doctors whereas psychiatrists are specialists that regularly see patients with depression. However, controversially, GP’s have previous knowledge of the patient prior to the depressive symptoms, allowing a more valid comparison. On the other hand, there are arguments to explain why GP’s diagnosis might lack validity. For example, Van Weel-Baumbarten et al. (2006) suggested that diagnoses made by GP’s may be less objective because they are based on previous knowledge of the patient and family history rather than the actual presenting symptoms (necessary for DSM diagnosis), meaning that the biased view from the GP causes the diagnosis to lack validity and therefore may not be reliable. Furthermore, Stirling et al. (2001) found that the average consultation time for a GP to diagnose depression was just over 8 minutes compared to 1 hour for a psychiatrist, in which demonstrates that a GP’s diagnosis is not thorough enough and collecting enough evidence from the patient to be able to be diagnosed and for it to be accurate. They also found that a GP was 32% more accurate in their diagnosis if they increased their appointment length by another 4 minutes. Hence, to improve the validity of diagnosis and classification of depression, GP’s need to have longer appointments and specialist training in mental health. Even better still, GP’s could refer patients onto specialists, such as psychiatrists, as their objectivity will increase the diagnostic validity.
Similarly, psychiatrists are more aware than GP’s that patients may be suffering from combined mental illnesses; otherwise known as co-morbidity. This is the extent to which two or more conditions co-occur, for example different subtypes of depression and anxiety. For instance, there is a high concordance rate between alcoholism, depression and anxiety disorders. It is common that anxiety sufferers also have a risk of developing depression. Because of this, it makes diagnosis difficult as it makes it challenging to diagnose the fundamental cause of the suffering. Research supports the issue that assessment tools are diagnosing patients with depression when in fact the symptoms may be caused by another disorder. Goodwin et al (2001), found that patients with depression are five times more likely to have suicidal thoughts than patients with no psychiatric disorders. Furthermore, if the sufferer has a panic disorder then the rate of suicidal thoughts increased to fifteen times more likely. Therefore, it is probable that the suicidal thoughts will be said to be caused by depression, and therefore the psychiatrist would treat the patient for depression, when in fact symptoms may be caused by a panic disorder. Therefore, this suggests that due to co-morbidity, classifications are invalid.
Not only are they invalid, they are also culturally biased. There is culture bias in diagnostic tools such as the DSM-IV as it was developed in a Western area, meaning it may overemphasise the western concept of mental health and ignore the role of cultural factors. The issues of this are that: in some cultures, some symptoms of mental illness such as hearing voices, may be seen as normal or special in other cultures, whereas in western cultures would be classed as symptoms of a mental illness. Furthermore, the same illness may manifest itself differently in different cultures. For example Ebigno (1986) found that symptoms of depression vary from culture to culture; in the West characteristics would be feelings of worthlessness and loss of interest, whereas in Nigeria (Eastern), people complain or burning sensations in the body and bloated feelings. Therefore, this suggests that classification is not generalizable to every culture, as symptoms vary from place to place. The DSM-IV may be valid to use in the West to diagnose depression, but not in the East.