Word-mint: Type 1 and 2 errors in diagnosis – WordMint
What does the term validity mean to you? When considering the validity of a diagnosis, we have to ask does the person REALLY have the condition they have been diagnosed with? May be they do not need a diagnosis at all? May be they have been diagnosed with a condition when in fact they don’t have that condition, in fact maybe they don’t have any psychiatric condition at all (Type 1 error) or maybe they have been deemed to have no condition at all, when in fact they perhaps do have a certain condition, (Type 2 error).
Can you think of any reason why it might be hard to make a VALID diagnosis? Think about how psychiatrists collect information about service users in order to make their decisions, think about cognitive psychology, how do people process information (SELECT, ORGANISE and INFER), what ideas do you about why a psychiatrist may find it hard to make a valid diagnosis.
Is psychiatric diagnosis an objective process? Think about how we might diagnose a broken leg or cancer? How does this differ to making a psychiatric diagnosis?
So, what does VALIDITY mean in this context?
In the context of diagnosis, validity refers to how accuracy, meaningfulness and usefulness of a diagnosis (Willerton et al 2013). An unreliable diagnosis, will not be a valid one, yet a reliable diagnosis does not mean the diagnosis is necessarily valid. We are going to learn about a few specific types of validity to help us discuss this topic in more detail. You should be able to use at least 3 of the following types of validity in your oral and written work.
- descriptive validity
- aetiological validity
- concurrent validity
- predictive validity
Types of validity: types-of-validity-improved
On the revision area for this topic there is a nice long essay, which combines all the different things that you need to know about regarding validity and reliability of diagnosis. Read the essay in order to find out about factors which can affect the validity of diagnosis. You will find out about:
- Top down processing
- Reading-in Syndrome
- Cognitive biases/Reconstructive Memory
- Selective Remembering
- The Primacy Effect
- Barriers to Communication
Make notes from the essay and once you feel more confident with the terms, use the sheet here to match the term to its definition, use colour coding to match them up:
Now you should be able to attempt a question:
Explain one issue relating to the validity of diagnosis using classification systems such as the DSM (3)
In order to test your knowledge of the different areas that you have looked at so far, try the following exercise, you need to say whether the scenarios relate to:
- good or bad reliability: test-rest or inter-rater reliability
- good or bad validity; concurrent, predictive, descriptive or aetiological
The Validity of the DSM
Waving goodbye to ‘Not Otherwise Specified’
A strength of DSM5, compared with, DSM IVTR is that practitioners should be able to reduce the use of the phrase ‘not otherwise specified’ (NOS), which is often added to the end of a more general diagnosis, e.g. ‘pervasive developmental disorder: (NOS).
Previously, practitioners had to decide whether specific symptoms were ‘present’ or ‘absent’, yet it is often difficult to discern how severe a symptom should be in order to ‘count’. This led to over-use of NOS as practitioners tried to avoid ‘getting it wrong’. DSM 5’s ‘dimensional approach’ avoids some of this by merging similar disorders and creating more spectrum disorders, (e.g. Asperger’s Syndrome is now part of Autistic Spectrum Disorder).
This is important development could make diagnosis more valid.
Competing argument: Despite some merging of some disorders that arguably improve the validity of diagnosis, the DSM 5 has also added some hotly contested new disorders such as ‘Disruptive Mood Dysregulation Disorder’ which is distinctly similar to the already existing diagnosis of Oppositional Defiant Disorder, which can be applied to children who are uncommonly irritable, argumentative and vindictive.
Concerns around lowered thresholds
One weakness of DSM5 is the ‘lowering of diagnostic thresholds’ for certain disorders, meaning not as many criteria need to be met in order to be diagnosed.
For example, there are particular concerns around disorders such as ‘Mild Neurocognitive Disorder’ which could lead to misdiagnosis of people who are elderly, who are displaying normal signs of ageing.
This is important as many argue the creation of disorders such as this will lead to the medicalisation of normal life stages.
Using research evidence to evaluate validity of diagnosis
In your textbook you can read about a study by Brown (2014) which is about the validity of the diagnosis of Anorexia using the DSM5; read the study and make a brain map to record the details; decide on some headings to structure your brainmap; what is the nature of each piece of information that you are being given, e.g. the first heading might be: problems with DSM5 for diagnosing Anorexia.
Think: What type of errors (type 1 and 2) might be creeping into diagnosis of anorexia due to change in DSM 5? Explain your choices.
Now, you need to look back at the studies that you sorted into reliability and validity. You should have had the following three studies in the validity pile:
- Kim Cohen
Read each study carefully and work out which types of validity are being demonstrated in the study. You could sue the studies to help explain the concepts if you need to. You could also use the studies as part of your evaluation of the validity of the DSM.
Finally do a little more reading from your textbook to answer the following question: How has section 3 (particularly) of the DSM 5 helped to improve the validity of diagnosis? (THINK CULTURE!)
Issues and debates
One issue relevant to classification systems is that of culture.
A literature review by Robert Schwartz and David Blankenship (2014) showed that Afro-Americans are more three to four times more likely to be diagnosed with a psychotic disorder than Euro-Americans. This means that a person’s ethnicity may affect the practitioner’s diagnosis as they will be more likely of diagnose a disorder which fits with stereotypical, schema knowledge.
This is important as an invalid diagnosis can lead to many negative outcomes including incorrect treatment and consequent side effects and stigmatisation, which may even lead to suicide, (Schwartz and Blankenship 2014).
Make a link – Individual differences
In some cases people with the same diagnosis present very different symptoms and this suggests that the disorder, in question, does not have good descriptive validity. Zutt (1967) coined the term ‘pathoplasticity’ to describe the fact that cultural differences can ‘shape’ the way in which a disorder manifests itself. One example of this is schizophrenia which has many and varied symptoms (see p 000). Kausar Suhail and Raymond Cochrane have shown that people diagnosed with schizophrenia from Pakistan were more likely to experience visual hallucinations including visualising ghosts and spirits than Pakistani and white people living in Britain with a diagnosis of schizophrenia. The latter groups were both more likely to experience auditory hallucinations than the people with schizophrenia living in Pakistan, (Suhail and Cochrane 2002).
You should be able to use everything you have learnt about to answer the following question.
With reference to research evidence, assess the validity of the DSM IV or 5 (8)
Remember as a 8 marker you need to follow AT/CH/OO/BC. Remember to balance the amount of AO1 and AO3. Importantly, the question requires you to make judgments about the validity of the DSM. You need to consider a range of factors which impact the validity and come to a conclusion.
Evaluation of the Validity of ICD
Good predictive validity for schizophrenia
One strength is that Peter Mason and colleagues (1997) have shown that the diagnosis of schizophrenia using the ICD-10 has good predictive validity.
The study compared different ways of making a diagnosis, including the use of ICD-9 and 10, in terms of their ability to accurately predict functioning in 99 people with schizophrenia. The ICD was ‘reasonably good at predicting disability’ 13 years later, as measured by the global assessment of functioning questionnaire.
This study shows that the initial diagnosis was useful and meaningful in terms of its ability to accurately predict future outcomes for people with schizophrenia compared to those without a diagnosis of schizophrenia.
One strength of the WHO’s approach to the development of ICD 11 is that they aim to improve the ‘clinical utility’ of this system.
This means the system should become more ‘user-friendly’; hopefully by virtue of being easier to use, validity of diagnosis should also improve. The WHO have conducted a huge international survey of clinicians and found a preference for simplicity and flexibility, suggesting that the ICD 11 task force will be cautious about adding new disorders and are likely to merge disorders that are difficult to diagnose.
You may be asked to evaluate the ICD with regard to validity, separately from the DSM, in which case you will need some studies which focus on ICD, in which case you can use:
- Pihlajamaa et al (2008)
- Jansson et al (2002)
The following articles will be helpful to enrich your answers:
Caetano et al (1974) original: http://www.jstor.org/stable/2137025?casa_token=4k29UQOebjQAAAAA:aVWbFaK0GPQzHI6t19manokxp6hD1ur4e0pDeFmAV82V_l-S0h1s93ejnj4usENf1Vhe-VilUwL4QBPXaYAQ3JMTtN5FdTPQ0K5QVSMYXdOU56U9GA&seq=2#page_scan_tab_contents
Kim -Cohen et al (2005) original paper: https://ajp.psychiatryonline.org/doi/pdfplus/10.1176/appi.ajp.162.6.1108
A great article for understanding the issues with validity and psychiatric diagnosis: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4780305/
- With reference to research evidence, assess the validity of ICD 10 (8)
- With reference to research evidence, assess the validity of DSM IV or V (8)
- Using research evidence, explain one strength of the DSM IV or V with regard to validity of diagnosis. (3)
- Using research evidence, explain one weakness of the DSM IV or V with regard to validity of diagnosis. (3)
- Using research evidence, explain one strength of the ICD 10 with regard to validity of diagnosis. (3)
- Using research evidence, explain one weakness of the ICD 10 with regard to validity of diagnosis. (3)
Try these questions once we have looked at the diagnosis of schizophrenia:
- Describe an issue associated with making a valid diagnosis of schizophrenia (3)
- Gerald’s son has just received a diagnosis of schizophrenia but he is concerned as he has watched a documentary that gives the impression that schizophrenia is a not a ‘valid’ diagnosis. The documentary included the following quote which has really got Gerald thinking:”‘How do we know that the patient has schizophrenia?’ ‘Because of the symptoms he experiences’, ‘Why does the patient experience symptoms?’, ‘Because he has schizophrenia.’”Explain whether Gerald should be concerned about his son’s diagnosis (4)