Depression- Issues surrounding the classification and diagnosis of MDD including reliability and validity Flashcards
What is validity?
• Validity is the extent to which the tool measuring MDD is measuring it accurately. • E.g. making sure that the DSM (Diagnostic and Statistical Manual of Mental Disorders) and a doctor diagnose depression in patients accurately and not another disorder.
What is concurrent validity?
• This is the extent to which a test to measure MDD concurs (agrees) with and already existing current measure of depression. • For example; the extent to which the BDI score for depression is the same as the Hamilton score for depression on the same patient.
AO2 for validity
I) A consequence of being given a valid diagnosis of depression is that it can lead to labelling. E) Diagnosing someone with a disorder means that we are labelling them and these labels can be extremely difficult to remove. Someone who has suffered from depression may always have the label ‘depressed; applied to them even if they haven’t had a symptom in a long time. The label of depressive stays with a person unlike the experience of having the flu for example. This means that when applying for jobs for example, could be difficult because as employers may not want to hire a person who they see as suffering from depression. C) This means that a valid diagnosis of depression can cause problems for people later in life.
AO2 for concurrent validity
I) A consequence of concurrent validity in the diagnosis of depression is that even id the BDI and Hamilton scale concur with each other and are valid measures of depression; a diagnosis is ultimately made by the patient’s local GP. E) Diagnoses made by GPs are made against a background of previous patient knowledge and could be biased as a result. For example, if the GP knows a patient has lost their job but tends to exaggerate their feelings he might ignore their symptoms of feeling worthless and suicidal. C) This means that an invalid diagnosis of depression might be made and a patient may believe that they do not have depression when in fact they do, and may be given the wrong treatment.
What is comorbidity validity
• This is where a patient gets diagnosed with MDD and another disorder. • For example, being diagnosed with depression and panic disorder.
First AO2 for comorbidity- Which caused the other?
I) A consequence with comorbidity in the diagnosis of depression is that it is difficult to know which is the main disorder and might lead to a misdiagnosis. E) Depression often occurs alongside disorders such as substance abuse, alcoholism and eating disorders, meaning that it can be hard for a clinician to decide which the main disorder is and which to treat. For example, is it the substance abuse that led the depression (meaning that the substance abuse needs to be treated), or is it the depression that led to the substance abuse, (so depression should be treated). C) This means that comorbidity can lead to an invalid diagnosis of depression, which means that the patient may not get treatment for the bigger issue.
Second AO2 for comorbidity- Goodwin
I) A consequence of comorbidity in the diagnosis of depression is that it can have a negative impact on the patient, making the depression worse. E) Goodwin (2001) found that the likelihood of having suicidal thoughts is five times higher in patients with MDD alone compared to those with no psychiatric disorder. However, patients with MDD co-morbid with panic disorder had triple that ratio (15x). C) This means that having a valid diagnosis in depression comorbid with another might make the depression even worse.
What is reliability?
• This is whether the instrument used to measure MDD is consistent. • For example; the extent to which the BDI score stays the same later the same day or the following week for one patient.
What is inter-rater reliability?
• This is whether two independent assessors give the same diagnosis of depression to the same patient.
First AO2 for inter-rater reliability- Different information given to different clinicians
I) A consequence of inter-rater reliability in the diagnosis of depression is that a patient might give different information to two different clinicians. E) It is very difficult for a patient to say the exact same thing on two differing occasions. When a patient is being clinically interviewed the clinician is relying on retrospective data. The problem with this is that some of the data will not apply to the patient at that moment in time- they may not be suffering with certain symptoms anymore but are still suffering from others. C) This means that one clinician might diagnose the depression and another might not, making the diagnosis unreliable. This therefore could lead to the misdiagnosis and incorrect treatment for the patient.
Second AO2 for inter-rater reliability- Keller
I) Keller has suggested another consequence of inter-rater reliability in the diagnosis of depression. E) In the diagnosis of MDD at least 5 symptoms need to be presentin the patient. If one of these symptoms is quite subtle in the patient it might mean that one clinician picks up on it and another misses it. (choose a symptom of MDD that might be subtle and missed by a doctor) For example, if sleep patterns are not quite right, one clinician may see this as insomnia, whilst another might not. C) This means that one clinician might diagnose the patient with MDD and the other might diagnose the patient with a lesser form of depression. This makes the diagnosis unreliable and can lead to a patient being wrongly diagnosed with having or not having depression.
What is test-retest reliability?
• This is the extent to which the tests used to diagnose MDD are consistent over time. • For example, if the BDI measures someone as depressed, whether it would the next day too.
AO2 for test-retest reliability- limited time
I) A consequence of test-retest reliability in the diagnosis of depression is that there is limited time and resources available especially in today’s economic climate. E) Many professionals are rushed and preoccupied, especially since todays health system has the aim of seeing as many patients as possible. Therefore there isn’t enough time for a clinician to see all of the symptoms at the first visit. Also one or two symptoms may not be present at the time of the first test but then may be evident at the time of the retest. C) This means that a patient may not be diagnosed with depression on the first test but may be on the second test. This makes the diagnosis unreliable and could lead to the incorrect diagnosis.
AO2- improving reliability and validity
I) As a result, the reliability and validity of the diagnosis and classification of depression needs to be improved to make sure that each patient is correctly identified as being depressed. E) In order to do this, Meehl (1977) suggests that mental health professionals should be able to count on the total reliability and validity of the diagnostic tools that they have at their disposal. Doctors must: • Pay close attention to medical records • Be serious about the process of diagnosis • Take account of the very thorough descriptions presented by the major classificatory systems. • Consider all of the evidence presented to them. C) This means that it is possible to increase the validity and reliability of the classification of depression if clinicians follow Meehls guidelines. This means that diagnosis’ are more likely to be correct and that patients will receive the correct treatment.
What were Meehl’s suggestions?
• Pay close attention to medical records • Be serious about the process of diagnosis • Take account of the very thorough descriptions presented by the major classificatory systems. • Consider all of the evidence presented to them.
