Outline and Evaluate Issues Relating to the Classification and Diagnosis of Schizophrenia

One of the issues related to the classification and diagnosis of schizophrenia is reliability. This refers to the consistency of a measuring instrument, such as DSM or ICD which are both slightly different to each other which means that someone may be diagnosed in one country and then be considered perfectly healthy in another country. Reliability can either be measured in terms of inter-rater reliability, which is the extent to which two or more independent assessors give a similar diagnosis, or in terms of test-retest reliability which is the extent to which the tests used to deliver these diagnoses are consistent over time.

It has been claimed that the DSM used to today (version five) is reliable. However, evidence shows that the reliability of DSM is low when assessed by inter-rater reliability. Whaley found only a small positive correlation of +11 between different raters. This is evidence for low reliability when using DSM to diagnose schizophrenia. Although, test-retest reliability studies have shown positive results. Prescott et al analysed the test-retest reliability of several measures of attention and information processing in 14 chronic schizophrenics. These measures were stable over a 6-month period. This shows that there is high test-retest reliability when using these measures of attention and information processing to diagnose schizophrenia.

In different cultures they may interpret schizophrenia differently which also poses a threat to the reliability of the diagnosis. For example, in China they are reluctant to diagnose someone with schizophrenia as it will have big implications for the individual’s job, social life and family. A study by Copeland et al compared 134 US psychiatrists and 194 British psychiatrists in their diagnosis of a patient, and found that 69% of the US psychiatrists diagnosed schizophrenia compared with only 2% of the British psychiatrists. This suggests that there is a massive variation between countries and it affects the...