Reliability and Validity in Diagnosis and Classification of Sz

Question 1

Outline reliability and validity in the diagnosis and classification of Sz (
6 marks)

Answer 1

Reliability refers to gaining consistent results when classifying and diagnosing Sz. Different classification systems should agree on how Sz should be classified. The extent to which 2 or more health professionals would agree on the same diagnosis, regardless of time period or culture measured by inter-rater reliability. Validity refers to accuracy where we measure what we intend to measure such as classification systems outlining the symptoms of Sz. For example, whether health professionals are accurately diagnosing Sz. Research by Cheniaux asked 2 psychiatrists to diagnose 100 patient using ICD and DSM. The first psychiatrist diagnosed 26 using DSM and 44 using the ICD. The second one diagnosed 13 using the DSM and 24 using the ICD. This shows low inter-rater reliability as there is a difference in diagnosis when using the different classification systems of Sz. Therefore may not be accurately classifying SZ so questions the validity of the diagnosis.

Question 2

Outline symptom overlap

Answer 2

Two or more conditions have similar symptoms. For example, both Sz and depression involve negative symptoms

Question 3

Outline co-morbidity

Answer 3

Two illnesses occur at the same time. For example, Sz is usually diagnosed with another illness like depression. This can lead to misdiagnosis

Question 4

Outline gender bias

Answer 4

Men diagnosed with Sz more than Women. Men may be more genetically vulnerable to Sz but females may be able to function better than men with Sz such as have good family relationships

Question 5

Outline culture bias

Answer 5

English people of African origin more likely to be diagnosed with Sz in the UK. Higher diagnosis due to behaviours and positive symptoms such as hearing voices seen as abnormal in UK compared to in Africa where it is more likely to be seen as a gift

Question 6

Evaluate reliability and validity in the diagnosis and classification of Sz (4 X AO3)

Answer 6

One problem of reliability and validity of the classification and diagnosis of schizophrenia is that there is often ‘Symptom overlap’. This is where two or more conditions share similar symptoms. For example, both schizophrenia and depression involve negative symptoms such as avolition. This questions the validity and reliability of the classification and diagnosis of schizophrenia 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 may not receive appropriate treatment. This weakens the validity and reliability in the classification and diagnosis of schizophrenia as it negatively affects its accuracy and consistency.

A further problem with the reliability and validity of the diagnosis and classification of schizophrenia is ‘Co-morbidity’. This is where two illnesses/conditions occur at the same time. For example, Buckley et al concluded that 50% of patients diagnosed with schizophrenia also have a diagnosis of depression and 23% of patients diagnosed with schizophrenia are diagnosed with OCD. This questions the validity and reliability of classification and diagnosis of schizophrenia, because the two conditions may be better seen as one and doctors may diagnose the wrong condition and may not receive appropriate treatment.

Moreover, another issue with the validity of the diagnosis and classification of schizophrenia is Gender bias in diagnosis. Since the 1980s men have been diagnosed with schizophrenia more often than women. This may be because men are more genetically vulnerable to developing schizophrenia than women. However, it could be because females with schizophrenia typically function better than men, being more likely to work and have good family relationships therefore their symptoms may be masked by good interpersonal skills. This questions the validity and reliability of the classification and diagnosis of schizophrenia as women who share similar symptoms as men may not receive the same diagnosis as their symptoms seem mild and may be more likely diagnosed with bipolar depression.

A final problem with the classification and diagnosis of schizophrenia is cultural bias. English people of African origin are much more likely to be diagnosed with schizophrenia in the UK. This is attributed to some Afro-Caribbean societies view hearing voices as communication from ancestors whereas in the UK this behaviour would be associated with positive symptoms of schizophrenia. Therefore, resulting in Afro- Caribbeans living in the UK being ten times more likely to receive a diagnosis for schizophrenia compared to white Britons. Thus, questioning the reliability and validity of the classification and diagnosis of Sz because clinicians may not fully understand other cultures so leads to problems in diagnosis and individuals may not receive appropriate treatment.