issues is diagnosis and classification of SZ

• strength of diagnosis of SZ = good reliability

  One strength of the diagnosis of SZ = its reliability. Reliability = consistency. A psychiatric diagnosis is said to be reliable when different diagnosing clinicians reach same diagnosis for same individual (inter-rater reliability) and when the same clinician reaches the same diagnosis for the same individual on two occasions (test-retest reliability). Prior to DSM-5, reliability for SZ diagnosis was low but has now improved.
• evidence for the reliability of SZ classification

  Osorio et al in 2019 report excellent reliability for the diagnosis of SZ in 180  individuals using the DSM-5. pairs of interviewers achieved inter rate reliability of +.97 and test-retest reliability of +.92. this means that we can be reasonably sure that the diagnosis of SZ is consistently applied.
• limitation = low validity

  validity concerns whether we asses what we are trying to assess. way of assessing validity of a psychiatric diagnosis is criterion validity. Cheniaux et al in 2009 had two psychiatrists independently assess the same 100 clients using ICD-10 and DSM-IV criteria and found that 68 were diagnosed with SZ under the ICD system and 39 under DSM. This suggests that SZ is either over or underdiagnosed according to the diagnostic system. Either way this suggests that criterion validity is low.
• good validity - counterpoint to bad validity

  In the Osorio et al study there was excellent agreement between clinicians when they used to measures to diagnose schizophrenia both derived from the DSM system. This means that the criterion validity for diagnosing schizophrenia is actually good provided it takes place within a single diagnostic system.
• limitation of SZ diagnosis = comorbidity with other conditions

  If conditions occur together a lot this calls into question validity of their diagnosis & classification because might actually be 1 condition. SZ is commonly diagnosed with other conditions. E.g. 1 review found that about 1/2 those diagnosed with SZ also had diagnosis of depression/substance abuse. This is a problem for classification because it means SZ may not exist as a distinct condition and is a problem for diagnosis as at least some people diagnosed with SZ may have unusual cases of conditions like depression
• limitation of SZ diagnosis = gender bias of classification

  Since the 1980s men have been diagnosed with SZ more commonly than women with a ratio of 1.4 : 1 (Fischer & Buchanan 2017). One poss explanation for this is that women are less vulnerable than men, perhaps because of genetic factors. However, it seems more likely that women are undiagnosed because they have closer relationships and hence get support. This underdiagnosis is a gender bias and means women may not therefore be receiving treatment and services that might benefit them.
• Culture bias

  Limitation in the diagnosis of mental health conditions
• Some symptoms of schizophrenia, particularly hearing voices, have different meanings in different cultures
• British people of African-Caribbean origin are up to 9x as likely to receive a diagnosis of schizophrenia as white British people
• People living in African-Caribbean countries are not more likely to receive a diagnosis, ruling out genetic vulnerability
• Most likely explanation

  Culture bias in diagnosis of clients by psychiatrists from a different cultural background
• This appears to lead to an overinterpretation of symptoms in black British people
• This means that British African-Caribbean people may be discriminated against by a culturally biased diagnostic system
• limitation = symptom overlap

  There is considerable overlap between symptoms of SZ & those of other conditions. e.g. both SZ & bipolar disorder involve +ve symptoms (delusions) and -ve symptoms (avolition). classification = suggests that SZ & bipolar disorder may not be two diff conditions but variations of 1 condition. diagnosis = it means that SZ = hard to distinguish from bipolar disorder. As with co-morbidity, symptom overlap means that SZ may not exist as a distinct condition and that even if it does it is hard to diagnose. So both its classification and diagnosis are flawed.