Diagnosis

=Discuss validity and reliability of diagnosis=

//**Discuss**// - DEFINE

How to deal with this learning outcome as an essay topic Use the questions in your packet – they are guiding you to think about the key issues

 **Reliability** ** Validity **  **Factors to consider**
 *  the extent to which different psychiatrists agree on a patient's diagnosis when using the same diagnostic system (inter-rater reliability)
 *  the extent to which the diagnosis is accurate
 *  can be limited by existence of culture-bound syndrome


 * Classification systems are descriptive and are often low in reliability
 * raters do not have 100% agreement and reliability differs
 * DSMIV = 64% agreement (Crane page 141)
 * Ormond Street system reliability of .88
 * ICD-10 - reliability of .36
 * doesn't mean that these systems are useless but it does mean that we cannot just accept diagnoses at face value
 * for these systems to be valid, they have to be able to isolate and identify patterns of symptoms
 * they only do this to a certain extent
 * Rosenhan study
 * Culture blindness (Crane page 146)

=Model for an essay outline=

**Introduction**
> – this is your thesis
 * Construct this in your own voice
 * Ultimately diagnosis is influenced by specific factors (as you know from your reading)
 * What are the key issues/arguments/hypotheses?
 * your introduction must identify the 3 you will discuss
 * You will see that the paragraph outlines below follow the question segments in your packet

**Paragraph I: setting up the foundation of your discussion**
Classification systems are central to this discussion
 * what does ‘diagnosis’ mean?
 * What makes diagnoses valid?
 * What makes them reliable?
 * How do we diagnose? – what systems have been created?

So – why are these classification systems central to any discussion of validity and reliability?


 * must be acknowledged that all systems have limitations
 * equally, just because systems exist, doesn’t mean they are correct
 * link back to how this relates to validity and reliability
 * All about context
 * Change over time
 * Differences in perception between culture

**Paragraph 2 - discussion of reliability**
To what extent are the diagnostic systems reliable?
 * Compare systems you know – do they agree on diagnoses? Do they have similarities? Differences? Is this a limitation? How does this affect validity and reliability
 * CCMD3
 * DSMIV
 * ICD-10

Overall, inter-rater reliability across, and even within a system is not high
 * Why not?
 * Evidence?
 * o Rosenhan (1973)
 * o Di Nardo (1993)
 * o Significance of this evidence in relation to reliability?

Psychiatrists - attitudes and prejudice affects diagnosis
 * Eg. Confirmation bias – Rosenhan
 * Impact on validity?

BUT SO
 * Reliability can apparently increase with continuous modification
 * Evidence – discussion of comparisons between DSM vs OCD vs Greater Ormond street
 * Make sure you discuss the significance of these in relation to the reliability of diagnosis
 * Inter-rater reliability can appear to increase with modification
 * But – is this only a surface improvement? What would happen if the test was used in a different culture? Can you support your prediction?
 * Focus on finishing off this discussion with a ‘big picture’ summary

**Paragraph 3: to what extent are the classification systems valid?**
Systems are necessary to diagnosis but cannot be said to have high validity

Then: Establish:
 * What makes them valid? Refer back to your earlier comments in paragraph I
 * Explain the relevant factors involved
 * Can physical signs be objectively identified?
 * What degree of validity do the manuals have?
 * BIAS in diagnosis can lead to lack of validity in the design of systems
 * Eg. DSMIV – limited because culture is not considered
 * Concepts of abnormality differ within cultures
 * CCMD-2 and shenjing shuairuo
 * If symptoms are classified differently then this reduces the validity of the systems

2 sentences is fine – go back to the command term, focus on the ‘big picture’, the ‘so what’
 * Overall conclusion**