A03: Classification & Diagnosis of Sz

• Evaluation Diagnosis & Classification A03:

  +veReliability

  -veReliability

  -ve: Validity

  +ve: Counterpoint to Validity

  Co-Morbidity

  -ve: Symptom Overlap

  Cultural Bias

  -ve: Gender Bias
• Reliability A03 - C&D

  P: Inter-rater reliability issues in diagnosing sz

  Inter rater reliability is extent different assessors agree on their assessments - consistency of diagnosis between clinicians

  2009, Cheniaux et al asked 2 psychiatrists to independently diagnose 100 patients using ICD & DSM psychiatric manuals.

  Found one psychiatrist diagnosed 26 (DSM) as sz & 44 (ICD). Other psychiatrist diagnosed 13 (DSM) as sz & 24 (ICD).

  L: Weakness in area of diagnosis coz show it vary depending on who making assessment & there fundamental lack of agreement amongst health care professionals.
• Co-Morbidity A03 - C&D - PART 1

  P: If conditions often coocur then they might be a single condition. Sz is commonly diagnosed with other conditions. So issues when classifying & diagnosing sz coz its high co-morbidity rates in sz suggest lack of understanding about it

  E: Buckley et al (2009) reviewed diagnoses of sz, found 50% of sz patients also diagnosed with depression - concluding that sz if co morbid with depression, substance abuse (47%), PTSD (29%) & OCD (23%). Poses challenges for diagnosis & classification of sz.
• Co-Morbidity A03 - C&D - PART 2

  E: If conditions occur together a lot of time it questions validity of diagnosis as may be mistakes in diagnosis

  L:This suggest may be an issue where psychiatrists unable to tell difference between 2 disorders OR that when 2 disorders appear in tandem that it may actually be totally different singular disorder. Regardless of which, we still dont fully understand sz & the symptoms which accompany it.

  Suggests that sz may not exist as a distinct condition
• -ve: Symptom Overlap A03 - C&D

  P: Issue with diagnosing sz is degree of similarity between this & other disorders

  E: The symptoms of sz overlap with many disorders like Bipolar disorder; involves +ve symptoms like delusional thinking & -ve symptoms like avolition

  L: This not only makes it difficult to distinguish between the 2 disorders but also questions whether these 2 similar disorders might actually by the same disorder. Meaning Sz may not exist as a condition and if it does its hard to diagnose.
• -ve: Gender Bias A03 - C&D

  P:Issue of gender bias in diagnosis of sz: more men vs women are diagnosed with sz

  Sz men more likely diagnosed vs women, at rate of 1:1.4 (Fischer & Buchanan 2017)

  Cotton et al (2009) suggest either coz men more genetically vulnerable OR women function better vs men; more likely work, have good/closer family relationships & more support

  L: This strong interpersonal functioning; mask symptoms/fact have sz OR severity. This questions validity as procedures for diagnosis work well only on patients of one gender. Means sz women not diagnosed so miss out on treatment.
• -ve: Validity A03 - C&D

  P: Criterion validity issues with diagnosing sz

  E: CV: extent different systems/procedure arrives at same diagnosis for same patient.

  E: Cheniaux et al, 2 psychiatrists independently reached diagnoses of sz more frequently using ICD (68 ICD & 39 DSM out of 100 clinets)

  E: So least one of manuals incorrect. Suggest using ICD leads to over diagnosis OR using DSM leads to under-diagnosis

  L: Problem coz show one of manuals not accurately measuring sz. As different manuals used in different countries then large n.o of patients -ve affected. So Criterion Validity is low.
• +ve: Counterpoint to Validity A03: C&D

  In the Osorio Study there was excellent agreement between clinicians is uing different procedures both derived from the DSM system.

  • This means that the Criterion validity for sz is good provided it takes place within a single diagnostic system
• +ve: reliablity A03: C&D

  • A reliable diagnosis is consistent between clinicians (inter rate) and between occasions (test -retest)
  • Osorio et al (2019) report excellent reliability for sz diagnosis (DSM-5) - inter-rater agreement of +0.97 and test-retest reliability of +0.92
  • This means that the diagnosis is consistently applied
• Cultural BiasA03 - C&D- PART 1


  High degree of cultural bias when diagnosing sz which evident by higher rates of diagnosis of both African-Caribbean & African-American people.  Symptoms like hearing voices accepted in some cultures like Afro-Caribbean societies 'hear voices' from ancestors.

  • Pinto & Jones (2008) found British people of Afro-Caribbean descent are 9x more likely to be diagnosed vs white British people. 

  But, this not true of those who live in Afro Caribbean countries
• Cultural BiasA03 - C&D- PART 2

  Suggests its unlikely to be genetic vulnerability & its in fact due to cultural bias where psychiatrists of different cultural background misinterpreting culturally specific behaviours as symptoms. Mean Afro-Caribbean in UK appear be discriminated against by a culturally-biased diagnostic system.
• Morbidity & Co-Morbidity DEF?

  Morbidity: Refers to a medical condition or how common it is

  Co-Morbidity: The phenomenon that 2 or more conditions occur together