reliability and validity of diagnosis

• What does reliability mean in the context of diagnosing schizophrenia?

  Consistent and replicable diagnosis
• How can reliability be tested?

  Test-retest or inter-rater reliability
• What is test-retest reliability?

  Consistency of diagnosis when repeated by the same clinician
• What is inter-rater reliability in the context of schizophrenia?

  Consistency of diagnosis when made by different clinicians
• What is test-retest reliability in the context of schizophrenia?


  The same clinician would make the same diagnosis again at a different point in time
• What could happen is a schizophrenia diagnosis wasn't reliable?

  A less reliable diagnosis is less likely to be valid
• What does validity mean in the context of diagnosing schizophrenia?

  Accuracy of clinicians' diagnoses and diagnostic criteria
• How can validity be assessed?

  Criterion validity
• What is criterion validity in the context of schizophrenia?

  Agreement of diagnosis between different assessment systems
• What are the potential consequences of an unreliable or invalid schizophrenia diagnosis?

  Inappropriate treatment or intervention
• What is meant by co-morbidity?

  When a person has more than one condition at the same time
• What is meant by symptom overlap?

  When two conditions have some effects in common
• What is meant by gender bias?

  Gender can distort the diagnosis, leading it to be less accurate
• What is meant by culture bias?

  Culture can distort the diagnosis, leading it to be less accurate
• What was reliability like prior to DSM-V?

  Low
• Cheniaux


  et al.(2009): How many did the first psychiatrist diagnose with schizophrenia?26 with schizophrenia according to the DSM and 44 according to the ICD
• What did Osório et al. (2019) report the test-retest reliability of schizophrenia to be?

  +.9
• What did Cheniaux


  et al.(2009) do?Had two psychiatrists independently diagnose 100 patients using both the DSM and the ICD criteria
• Cheniaux


  et al.(2009): How many did the second psychiatrist diagnose with schizophrenia?13 according to the DSM and 24 according to the ICD
• What impact does the criterion validity have on the diagnosis of schizophrenia?

  Either schizophrenia is over diagnosed in ICD or underdiagnosed in DSM, poor validity regardless
• Does diagnosing schizophrenia have criterion validity? Explain how.

  This suggests that schizophrenia does not have criterion validity as it is more likely to be diagnosed using ICD than DSM
• What are some common psychiatric co-morbidities among patients with schizophrenia?

  Substance abuse, anxiety, depression
• What percentage of patients with schizophrenia have co-morbid depression?

  50%
• What percentage of patients with schizophrenia have a lifetime diagnosis of co-morbid substance abuse?

  47%
• What percentage of patients with schizophrenia have PTSD?

  29%
• What percentage of patients with schizophrenia have OCD?

  23%
• What does the high prevalence of psychiatric co-morbidities suggest about the classification of schizophrenia? How?

  Weakens validity: perhaps they are not two separate disorders but rather, a single disorder
• What symptoms do schizophrenia and bipolar disorder have in common?

  Delusions, avolition
• Under which diagnostic criteria would a patient with symptoms of delusions and avolition be diagnosed as schizophrenia?

  ICD
• Under which diagnostic criteria would a patient with symptoms of delusions and avolition be diagnosed as bipolar disorder?

  DSM
• What does the overlap of symptoms between schizophrenia and bipolar disorder suggest about the two disorders?

  Suggests that schizophrenia & bipolar may not be two separate conditions but one
• What does the overlap of symptoms between schizophrenia and bipolar disorder suggest?

  Weakens validity
• What did Longenecker et al. (2010) conclude about the diagnosis of schizophrenia in men and women?


  Men have been diagnosed with schizophrenia more often than women. Female patients typically function better than male patients.
• According to Cotton et al. (2009), how do female patients with schizophrenia typically fare in terms of work and family relationships?


  Female patients typically function better than male patients. They are more likely to have closer relationships and hence get more support
• Why might women be under-diagnosed with schizophrenia?

  Women's better interpersonal skills may bias practitioners
• What does the under-diagnosis of women with schizophrenia suggest about the validity of the diagnosis?


  The validity of the diagnosis of schizophrenia may be poor, as the diagnostic procedures may work well only on patients of one gender.
• Which ethnic groups are more likely to be diagnosed with schizophrenia in America and England?

  African Americans and English people of Afro Caribbean origin.
• Are schizophrenia rates high in Africa and the West Indies?


  No, schizophrenia rates are not high in Africa and the West Indies.
• What does the low schizophrenia rates in Africa and the West Indies suggest about the high diagnosis rates in America and England?


  High diagnosis rates in America and England are not due to genetics.
• Why might there be a culture bias in the diagnosis of schizophrenia?

  Positive symptoms such as hearing voices are more acceptable in African cultures due to cultural beliefs of communicating with ancestors.