reliability of diagnosis

• when is diagnosis considered reliable?

  if different practitioners arrive at the same diagnosis of a patient (inter-rater reliability).

  • early versions of DSM were low, Spitzer and Williams (1985) reviewed process of diagnosis, suggesting experienced psychiatrists only agree 50% of the time.
  • Ward (1962), studies 2 psychiatrists diagnosing same patient, found disagreement occurred due to patient info provided (5%), psychiatrists interpretation (32.5%), inadequacy of classification system (62.5%).
• strengths of reliability of diagnosis?

  • move to criterion- based symptom where checklists are in place increases reliability.
  • Brown (2002), tested reliability of DSM IV diagnosis for anxiety or mood disorders, found to be good-excellent.
• what factor to do with giving different information impacts reliability of diagnosis?

  patient factors, different diagnoses to same person can be seen (can be due to lack fo standardisation in interview techniques
• what factor to do with the use of the classification system impacts the reliability of diagnosis?

  clinician factors, practitioner using systems aren't completely objective.

  • may gather insufficient info or not use categories of system correctly.
  • may not have sufficient time to spend on necessary structured interviews and rating scales, or using these instruments can affect rapport necessary for successful treatment
• what factor to do with equipment used impacts the reliability of diagnosis?

  classification system, DSM-5 has clear set of criteria which increases reliability. If 2 or more clinicians use same standardised set of criteria, more likely to agree on diagnosis improving inter-rater reliability.

  Criterion based coding also allows clinicians to use diagnostic tool in specific objective manner

  • Stinchfield (2016), researched gambling disorder for past 15 years and able to identify patients from treatment programme in Ontario as having/ not having gambling disorder.
• evidence for improving reliability of diagnosis?

  • improved with use of standardised interview schedules, giving instructions on how to rate severity for example.
  • Pederson (2001), 71% psychiatrists agree with ICD-10 definition of depression when assessing 116 patients, showing high inter-rater reliability.