Validity and reliability of diagnosis
Intro
validity of a diagnosis is whether the diagnosis is correct and leads to a successful treatment.
reliability of a diagnosis is whether two or more psychiatrists using the same classification system make the same diagnosis.
if a diagnosis is not reliable it cannot be valid.
Rosenhan - 4 points
Rosenhan had a group of students play the role of confederates, going into different psychiatric hospitals and claiming that they heard a voice saying, “One, two, three, thud.” once admitted they immediately stopped saying that they had symptoms, but were still kept in hospital. Once released, they were diagnosed with schizophrenia in remission. The study claimed to show that the doctors did not make a valid diagnosis – and argued that the validity of diagnosis is problematic at best.
1st point - researcher bias
Rosenhan argues that the nurses noted that the pseudopatients took extensive notes. He says that this was “seen as an aspect of their pathological behaviour.” However, the nurses’ notes simply said: “engages in writing behaviour.” The fact that Rosenhan reads so much into the nurse's notes is an example of researcher bias. The behaviours of the staff were recorded by the “patients” themselves. They wrote about how their behaviours were perceived by the hospital staff. It is impossible for anyone to corroborate or refute this account of how the pseudopatients were treated by the staff. The study suffers from researcher bias, where those that were being observed assumed the intentions of the nurses on staff. This makes it less valid as the opinions of those researching can affect the findings meaning it isn't completely reflective of real life and only of the beliefs of rosenhan and the pseudopatients. This in turn makes it unreliable as with each researcher the findings will alter as their opinions will differ from the next.
Point 2 - deception
However, this study has been challenged. First, the study was based on deception. One of the difficulties of making a valid diagnosis is that psychiatrists are dependent on self-reported symptoms. In this case, the “patients” lied about their symptoms. As patients cannot be tested for auditory hallucinations, it is not possible to verify their symptoms. This trust between a doctor and a patient is key to a valid diagnosis.
Point 3 - symptoms
disorders are “clusters of symptoms” and many symptoms are representative of several different disorders. This also influences the validity of diagnosis. In this case, the study is old and based on the DSM III. At that time, auditory hallucinations were considered to be a sign of schizophrenia. Today, no single symptom would be used to make a diagnosis. A problem, however, is that there are no blood tests that can be given to test for the disorder, although it is possible that in the future genetic testing may make diagnosis both more valid and reliable.
Lipton & Simon (1985)
. The researchers randomly selected 131 patients in a hospital in New York. All of the patients had been diagnosed with a psychological disorder. Seven clinical experts at the Manhattan Psychiatric Center reevaluated the selected patients and their diagnosis was then compared with the original diagnosis. Of the original 89 diagnoses of schizophrenia, only 16 received the same diagnosis on re-evaluation; 50 were diagnosed with a mood disorder, even though only 15 had been diagnosed with such a disorder initially. Such results indicate that the same symptoms may not necessarily lead to the same diagnosis by a different psychiatrist. This study demonstrates the importance of having more than one professional give a diagnosis.
One of the limitations of the Lipton & Simon study was that patients were already undergoing treatment. This may have led to changes in symptoms and could be one reason for the different diagnoses. Studying the reliability of diagnosis in a naturalistic setting presents such problems, and this could be a reason for why less ecologically valid approaches are often used.
Lobbestael, Leurgans & Arntz (2011)
investigated the reliability of diagnosis using the DSM IV with a sample of 151 participants, consisting of both patients and non-patients. The original clinical interviews, often lasting up to two hours, were audio-taped. The interviews were then assessed by a second psychiatrist who did not know the diagnosis made by the first psychiatrist.
-The results showed that generally there was higher reliability for personality disorders over other disorders. There was a 71 per cent rate of reliability in the diagnosis of major depression, whereas there was an 84 per cent rate of reliability of personality disorders. The high rate of consistency in diagnosis indicates that a diagnostic manual like the DSM IV, in this case, ensures that clinicians are more in agreement on a diagnosis. But even if the diagnosis is reliable, that does not necessarily mean that it is valid.
-A strength of this study is that the researchers used a single-blind procedure - the second psychiatrist did not know the diagnosis made by the first psychiatrist. Also, by using only audiotapes, non-verbal behaviour or the appearance of the patient did not affect the diagnosis process. However, this can also be seen as a limitation. It is difficult to know the extent to which non-verbal behaviour may have played a role in the first diagnosis. Therefore, the second diagnosis may be too controlled and could have missed important non-verbal data which may have changed the diagnosis.
-Even though psychiatrists use the same diagnostic tools, they may come up with a different diagnosis. One of the questions that need to be answered is – is it the diagnostic tool itself that is the problem? Or are there also other factors that may affect how a psychiatrist makes a diagnosis?
Authors note: we back and at it again bois, with it being mock season and final exams just around the corner here is some juicy final year psychology abnormal essays, good luck kids and stay tuned for some funky essays!