Reliability And Validity In Diagnosis And Classification Flashcards
Define reliability
Is consistency - the consistency of measurements
What is the difference between test-retest reliability and inter-rater reliability?
Test retest reliability is when clinicians reach the same conclusions at two different points in time
Whereas
Inter rater reliability is when different clinicians reach the same conclusions
What is a good kappa score and what is the score of the diagnosis of schizophrenia?
Above 0.7 is considered good. 1 = perfect
The diagnosis of schizophrenia had a kappa score of only 0.46 (Regier at al 2013)
State the differences in findings that culture had in the diagnosis of schizophrenia
1) Copeland (1971) gave 134 US and 194 British psychiatrists a description of a patient»_space;»
69% of US = schizophrenia
2% of British = schizophrenia
2) Lugrmann et al (2015) studied voices, 20 in Ghana, 20 in India, 20 in USA»_space;»>
Africans and Indians = positive voices
USA = negative voices
Luhrmann suggests that the harsh, violent voices so common in the West may not be an inevitable feature of schizophrenia
Define validity
Refers to the extent that a diagnosis represents something that is real and distinct from other disorders and the extent to which classification systems such as DSM 5 measures what it claims to measure
State the 3 validity issues in the diagnosis and classification of schizophrenia
1) Gender bias in diagnosis
2) Symtom overlap
3) Co-morbidity
What is the issue with gender bias in diagnosis?
Refers to the tendency to describe the behaviour of men and women in psychological theory and research in such a way that might not be seen to represent accurately the characteristics of either one of these genders
What is symptom overlap?
Refers to the fact that symptoms of a disorder may not be unique to that disorder but may also be found in other disorders, making diagnosis difficult.
What is co-morbidity?
Refers to the extent that two (or more) conditions or diseases occur simultaneously in a patient, for example schizophrenia and depression.
A01 - What is the research evidence for co-morbidity ?
A meta-analysis by Swets et al (2014) found that at least 12% of patients with schizophrenia also fulfilled the diagnostic criteria for OCD and about 25% displayed significant obsessive-compulsive symptoms.
(AO3) What is a weakness of inter-rater reliability?
P: Lack of inter-rater reliability
E: Whaley found 0.11 correlation in the diagnosis of schizophrenia
E: Suggests that, because psychiatric diagnosis lacks some of the more objective measures enjoyed by other branches of medicine, it inevitably faces additional challenges with inter-rater reliability.
(AO3) Why are the symptoms unreliable when diagnosing schizophrenia?
P: For a diagnosis of schizophrenia, only one characteristic symptom is required for example ‘bizarre delusions’.
E: When 50 psychiatrists in the US were asked to differentiate between. ‘bizarre and non-bizarre’ delusions, inter-rater reliability was only 0.4.
E: Shows a lack of sufficient reliability for it to be a reliable method of distinguishing between schizophrenic and non-schizophrenic patients.
(AO3) What was the research support that showed cultural differences in the diagnosis of schizophrenia?
P: Research (Barnes, 2004) showed cultural differences in the diagnosis of schizophrenia. However, the prognosis for those in ethnic minorities may be more positive than for majority group members
E: The ethnic culture hypothesis predicts ethnic minority experience less distress associated with mental disorders due to their environment. Research by Brekke and Barrio (1997) found evidence to support this in a study of 184 individuals with schizophrenia from two ethnic minority groups (Africans and Latinos) and a majority group (white Americans).
E:Results supported the ethnic minority hypothesis, found majority group members were consistently more symptomatic than the ethnic minority group.
(AO3) What is a strength of the validity issue of gender bias in diagnosis?
P: There is research support. Loring and Powell (1998) found evidence of gender bias by psychiatrists.
E:They randomly selected 290 psychiatrists who were asked to offer their judgment using standard diagnostic criteria about a patients behaviour. 56% diagnosed, when the patient was described as a male or no gender was given. 20% when described as female.
E: This gender bias was not evident among female psychiatrists, suggesting that diagnosis is influenced not only by the gender of the patient but by the gender of the clinician also
(A03) What is the consequences of co-morbidity?
P: A number of studies have examined single co-morbidities with schizophrenia, but these studies usually involve small sample sizes.
E: By contrast, Weber et al (2009) looked at nearly 6 million hospital discharge records and found evidence of many co-morbid non-psychiatric diagnoses like asthma and type 2 diabetes.
E: The authors concluded that the very nature of a diagnosis of a psychiatric disorder is that patients tend to receive a lower standard medical care, which in turn adversely affects the prognosis for patients with schizophrenia.
