Schizophrenia AO3

• +Good reliability. A reliable diagnosis is consistent between clinicians (inter-rater) and between occasions (test-retest). Osório reported excellent reliability for schizophrenia diagnosis (DSM-5) - inter-rater agreement of +0.97 and test-retest reliability of +0.92. This means that the diagnosis of schizophrenia is consistently applied.
• -Poor validity. Criterion validity involves seeing whether different procedures used to assess the same individuals arrive at the same diagnosis. Cheniaux had two psychiatrists independently assess the same 100 clients. 68 were diagnosed with schizophrenia with ICD and 39 with DSM. This means that schizophrenia is either over- or under-diagnosed, suggesting that criterion validity is low.
• +In the Osório study there was excellent agreement between clinicians using different procedures both derived from the DSM system. This means that the criterion validity for schizophrenia is good provided it takes place within a single diagnostic system.
• -Co-morbidity with other conditions. If conditions often co-occur then they might be a single condition. Schizophrenia is commonly diagnosed with other conditions. Buckley concluded that schizophrenia is co-morbid with depression (50% of cases), substance abuse (47%) or OCD (23%). This suggests that schizophrenia may not exist as a distinct condition.
• -Gender bias. Men are diagnosed with schizophrenia more often than women, in a ratio of 1:4 (Fischer and Buchanan). This could be because men are more genetically vulnerable, or women have better social support, masking symptoms. This means that some women with schizophrenia are not diagnosed so miss out on helpful treatment.
• -Culture bias. Some symptoms e.g. hearing voices, are accepted in some cultures, e.g. Afro-Caribbean societies 'hear voices' from ancestors. Afro-Caribbean British men are up to ten times more likely to receive a diagnosis as white British men, probably due to over-interpretation of symptoms by UK psychiatrists. This means that Afro-Caribbean men living in the UK appear to be discriminated against by a culturally-biased diagnostic system.
• -Symptom overlap. There is overlap between the symptoms of schizophrenia and other conditions e.g. both schizophrenia and bipolar disorder involve delusions and avolition. Schizophrenia and bipolar disorder may be the same condition a classification issue). Schizophrenia is hard to distinguish from bipolar disorder (a diagnosis issue). This means that schizophrenia may not exist as a condition and, if it does, it is hard to diagnose.