Classification and diagnosis of schizophrenia evaluation

  • Created by: gemshort
  • Created on: 15-04-18 12:52

Weakness - poor reliability
Elie Cheniaux et al (2009) had two psychiatrists independently diagnose 100 patients using both the DSM and ICD criteria. Inter-rater reliability was poor, with one psychiatrist diagnosing 26 with schizophrenia according to the DSM and 44 according to the ICD, and the other diagnosing 13 according to the DSM and 24 according to the ICD. This poor inter-rater reliability is a weakness of the diagnosis of schizophrenia

Weakness - poor validity
One standard way to assess the validity of a diagnosis is criterion validity: do different assessment systems arrive at the same diagnosis for the same patient? Looking at the figures in the Cheniaux et al study, we can see that schizophrenia is much more likely to be diagnosed using the ICD than DSM. This suggests that schizophrenia is either over-diagnosed in ICD or under-diagnosed in DSM; either way, this is poor validity and is a weakness of diagnosis

Weakness - comorbidity
Comorbidity is the phenomenon of two or more conditions occuring together. If conditions occur together, then this calls into question the validity of their diagnosis and classification because they might actually be a single condition. Schizophrenia is commonly diagnosed with other conditions. In one review, Peter Buckley et al (2009) concluded that around half of patients with a diagnosis of schizophrenia also had a diagnosis of depression (50%) or substance abuse (47%); PTSD also occurred in 29% of cases and OCD in 23% of cases

This poses a challenge for

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