Discussion of Issues Surrounding the Classification and Diagnosis of Schizophrenia
Discussion of Issues Surrounding the Classification and Diagnosis of Schizophrenia
One issue related to classification and diagnosis is reliability. Reliability refers to the consistency of a measuring instrument, such as DSM (the Diagnostic and Statistical Manual) that is used when diagnosing schizophrenia. Reliability can be measured in terms of whether two independent assessors give similar scores (inter-rater reliability). High reliability is indicated by a high positive correlation. Inter-rater reliability has been assessed for diagnoses of schizophrenia and found to be relatively low. This was especially true for earlier versions of DSM but it was hoped that later revisions of DSM would prove more reliable. However, more recent versions have continued to produce low inter-rater reliability scores. For example, Whaley (2001) found only a small positive correlation of +0.11 between different raters. Differences in cultural interpretations also pose a threat to the reliability of the diagnosis of schizophrenia. A research study by Copeland et al. (1971) gave a description of a patient showing clinical characteristics associated with schizophrenia to US and UK psychiatrists. Of the US psychiatrists, 69% diagnosed schizophrenia, whereas only 2% of the UK psychiatrists gave the same diagnosis. This suggests that the diagnostic criteria had quite a different meaning in different cultures and therefore are not reliable when used in different cultural settings. Reliability is also an issue for diagnosis. This was raised by Rosenhan (1973) who claimed that situational factors were more important in determining the ultimate diagnosis of schizophrenia, rather than any specific characteristics of the person. Rosenhan demonstrated this in his well-known study called ‘Sane in insane places’. He arranged for ‘pseudopatients’ to present themselves to psychiatric hospitals claiming to be hearing voices (a symptom of schizophrenia). All were diagnosed with
One issue related to classification and diagnosis is reliability. Reliability refers to the consistency of a measuring instrument, such as DSM (the Diagnostic and Statistical Manual) that is used when diagnosing schizophrenia. Reliability can be measured in terms of whether two independent assessors give similar scores (inter-rater reliability). High reliability is indicated by a high positive correlation. Inter-rater reliability has been assessed for diagnoses of schizophrenia and found to be relatively low. This was especially true for earlier versions of DSM but it was hoped that later revisions of DSM would prove more reliable. However, more recent versions have continued to produce low inter-rater reliability scores. For example, Whaley (2001) found only a small positive correlation of +0.11 between different raters. Differences in cultural interpretations also pose a threat to the reliability of the diagnosis of schizophrenia. A research study by Copeland et al. (1971) gave a description of a patient showing clinical characteristics associated with schizophrenia to US and UK psychiatrists. Of the US psychiatrists, 69% diagnosed schizophrenia, whereas only 2% of the UK psychiatrists gave the same diagnosis. This suggests that the diagnostic criteria had quite a different meaning in different cultures and therefore are not reliable when used in different cultural settings. Reliability is also an issue for diagnosis. This was raised by Rosenhan (1973) who claimed that situational factors were more important in determining the ultimate diagnosis of schizophrenia, rather than any specific characteristics of the person. Rosenhan demonstrated this in his well-known study called ‘Sane in insane places’. He arranged for ‘pseudopatients’ to present themselves to psychiatric hospitals claiming to be hearing voices (a symptom of schizophrenia). All were diagnosed with