Reliability and Validity in diagnosis and classification Flashcards
Definition of diagnosis
Identification of the nature of an illness by examining symptoms e.g. someone reporting hearing voices
Definition of classification
Action or process of categorising something - classification of disease according to symptoms e.g. symptom of SZ is hallucinations
AO1
Reliability and validity in classification and diagnosis of SZ was conducted by Cheniaux. They asked two psychiatrists to diagnose the same 100 patients using DSM and ICD.
Reliability refers to whether we can gain consistent results when classifying and diagnosing SZ. It’s the extent to which ICD and DSM consistently agree how SZ should be classified. Along with the extent to which two or more health professionals consistently agree on the same diagnosis measuring inter-rater reliability. In Chenaux’s study one psychiatrist diagnosed 26 people using DSM and the other diagnosed 13 having SZ. Using ICD one psychiatrist diagnosed 44 people and the other diagnosed 24 people with SZ. This shows poor inter-rate reliability as one diagnosed almost double than the other.
Validity is the extent we are accurately identifying SZ symptoms in an individual . It’s the extent which the ICD and DSM accurately identify SZ. Its the extent which two or more health care professionals accurately diagnose SZ when using the classification systems. Chenaux diagnosed almost double the patients using the ICD compered to the DSM which questions hw accurate the ICD and DSM outline symptoms of SZ
What is symptom overlap?
Two or more conditions share similar symptoms e.g. SZ and depression with involve negative symptoms such as avolition.
What is co-morbidity?
Where two illness occur at the same time. SZ is commonly diagnosed with other conditions such as depression/OCD as they are common symptoms e.g. lowered mood. This means SZ may not exist as a distinct condition which may lead to misdiagnosis.
What is gender bias?
Since 1980s men have been diagnosed with SZ more than women. Men are more genetically vulnerable to developing SZ hoover it could be because females with SZ typically function better then men and are more likely to work and have good family relationships
What is culture bias?
English people of African origin are more likely to be diagnosed with SZ in the UK. Higher diagnosis rates in the UK may be because some behaviours that are class as positive symptoms in SZ are normal in African culture e.g. hearing voices as part of ancestor communication.
What are the four evaluation points?
1) Symptom overlap
2) Co-morbidity
3) Gender bias
4) Culture bias
AO3: Symptom overlap
One problem of the reliability and validity of the classification and diagnosis of SZ is that there is symptom overlap. This is where two or more conditions share similar symptoms. For example both SZ and depression involved negative symptoms such as avolition. This questions the reliability and validity of the classification and diagnosis of SZ because an individual may be diagnosed with the wrong disorder. This is an issue as doctors may not be diagnosing SZ correctly and therefore individuals won’t receive the correct treatment. The weakens the validity of the reliability and validity of the classification and diagnosis of SZ as it negatively affects its reliability and accuracy.
AO3: Co-morbidity
A further problem with the reliability and validity of the classification and diagnosis of SZ is co-morbidity. This is where two illnesses occur at the same time. For example Buckley et al concluded that 50% of patients diagnosed with SZ also have a diagnosis of depression and 23% of patients with SZ also had OCD. This is an issue as doctors may not be diagnosing SZ correctly and therefore individuals may not be receiving appropriate treatment. This weakens the reliability and validity of the classification and diagnosis of SZ as it negatively affects consistency and accuracy.
AO3: Gender bias
Another issue with the reliability and validity of the classification and diagnosis of SZ is gender bias. Since the 1980s men have been diagnosed with SZ more often than women. However it could be because men are more genetically vulnerable to developing SZ compared to women. However it could be because females with SZ typically function better than mean being more likely to work and have good family relationships therefore their symptoms may be masked with good interpersonal skills. This questions the reliability and validity of the classification and diagnosis of SZ as women who share similar symptoms with men may not receive the same diagnosis as their symptoms seem mild.
AO3: Culture bias
A final problem with the reliability and validity of the classification and diagnosis of SZ is culture bias. English people of African origin are more likely to be diagnosed with SZ in the UK. This is attributed to some afro-carribean societies viewing hearing voices as communication from ancestors whereas in the UK this would be associated with positive symptoms of SZ. Therefore afro-caribbeans living in the UK are ten times more likely to receive a diagnosis of SZ compared to white Britons. This questions the reliability and validity of the classification and diagnosis of SZ as a persons culture is impacting the likelihood of being diagnosed with SZ.
