Diagnosis

• Reliability

  • Consistency over time and between professionals
  • Inter-rater reliability:
  • Extent 2+ professionals give same diagnosis
  • PPV (positive predictive value): 90 for schizophrenia so 90% diagnosed receive it again if reassessed
  • Patient factors (unreliable):
  • Poor recall
  • Denial, shame and fear of judgement/labelling
  • Clinician factors:
  • Subjective (own experience, training and background)
  • Unstructured interviews lead professional to different symptoms
  • Diagnostic system factors (low standardise/objective):
  • DSM uses using social norms
  • Inconsistent interpretation
• Validity

  • Extent diagnosis reflects actual disorder
  • MHD operationalised (made measurable) to be in DSM/ICD
  • Reducing disorder to finite symptoms may be inaccurate
  • Reductionist validity issue
  • Content change lowers validity of older classification systems; e.g. homosexuality once considered MHD, validity improved?
  • If unreliable, invalid; if different diagnoses are given, at least one diagnoses is invalid
  • DSM-5 removed “culture-bound syndromes”
  • Co-morbidity: Hard to diagnose with classification systems, relies on choosing “best fit” diagnosis using symptom set, lead to poor validity
• Gender + Culture

  • Cultures have different MH attitudes, impacting diagnosis, symptom reporting + prognosis
  • Gender: Culture affect diagnosis frequency per genders
  • Language Issues:
  • Translation issues
  • May misunderstand questions
  • Psychiatrist may misunderstand them
  • Views on mind/body:
  • West see separate
  • Others see integrated, reject over medicalisation
  • Culture-Bound Syndromes:
  • MH disorders isolated to 1 culture
  • Not universal, in DSM-IV not DSM-5
  • E.g. Hikikomori:
  • Adolescents completely withdraw from social life
  • Seek solitary confinement for prolonged periods, at extreme even 20 years
  • Japan