SARAH MOHAMED
Discuss issues surrounding the classification and diagnosis of
schizophrenia, including reliability and validity
Reliability refers to the consistency of a classification and diagnosis
system. One way reliability can be determined is through inter-rater
reliability which measures the percentage of homogeneity of a diagnosis
between two independent assessors. Another method of measuring
reliability is through test retest reliability which assesses the consistency
of a classification and diagnosis system over time. Beck et al found a 54%
homogeneity rate on diagnosis between two independent assessors. This
is very low compared to physical ailments which would be 90 -100%. This
could be attributed to the vague criteria of the classification and diagnosis
systems which leave possibilities for a wide range of interpretations. This
is heightened by the diversity of schizophrenic symptoms such as
hallucinations, delusions, speech disorders and many more. Therefore
diagnosis would be based on the subjective interpretation of the assessor
which could led to patients with schizophrenia not being identified and
treated and those who don’t being labelled as schizophrenic. However
Beck’s study should be viewed with caution as it may be a product of its
time as it was conducted in 1962 and the classification system i.e. DSM I
was vague. Many attempts have been made in order to address the issue
of reliability, with the DSM operationalizing more of its key terms for the
disorder within the third edition. Carson claimed that reliability issues
have been overcome with the release of the DSM III. However recent
studies such as Whaley have found a low inter-rater reliability of +0.11.
This suggest that 30 years on and issues of reliability have not been
overcome.
While the DSM is used in the US and UK the ICD is used in the rest of
Europe. The DSM is a multi-axial system which considers several different
factors such as an individual’s biological, physiological state and social
functioning when making a diagnosis. Whereas the ICD ignores other
factors and provides emphasis on first rank symptoms during diagnosis.
Firstly the ICD classification system appears to offer some advantages
over the DSM as the symptoms are only needed to be present for a month
whereas the DSM requires 6 months. This could pose a problem as
sufferers have to live for 6 months without receiving diagnosis and
therefore treatment. This increases the chance of sufferers becoming a
risk to themselves and others. However some may argue that the ICD’s
short period of a month required for diagnosis could led to labelling
individuals as schizophrenic when their symptoms may be due to a short
phase or life events such as bereavement etc. This has been
demonstrated by Rosenhan’s study
The problems with the medical classification has been highlighted by
Rosenhan. He found that psychiatrists could not reliably distinguish
Discuss issues surrounding the classification and diagnosis of
schizophrenia, including reliability and validity
Reliability refers to the consistency of a classification and diagnosis
system. One way reliability can be determined is through inter-rater
reliability which measures the percentage of homogeneity of a diagnosis
between two independent assessors. Another method of measuring
reliability is through test retest reliability which assesses the consistency
of a classification and diagnosis system over time. Beck et al found a 54%
homogeneity rate on diagnosis between two independent assessors. This
is very low compared to physical ailments which would be 90 -100%. This
could be attributed to the vague criteria of the classification and diagnosis
systems which leave possibilities for a wide range of interpretations. This
is heightened by the diversity of schizophrenic symptoms such as
hallucinations, delusions, speech disorders and many more. Therefore
diagnosis would be based on the subjective interpretation of the assessor
which could led to patients with schizophrenia not being identified and
treated and those who don’t being labelled as schizophrenic. However
Beck’s study should be viewed with caution as it may be a product of its
time as it was conducted in 1962 and the classification system i.e. DSM I
was vague. Many attempts have been made in order to address the issue
of reliability, with the DSM operationalizing more of its key terms for the
disorder within the third edition. Carson claimed that reliability issues
have been overcome with the release of the DSM III. However recent
studies such as Whaley have found a low inter-rater reliability of +0.11.
This suggest that 30 years on and issues of reliability have not been
overcome.
While the DSM is used in the US and UK the ICD is used in the rest of
Europe. The DSM is a multi-axial system which considers several different
factors such as an individual’s biological, physiological state and social
functioning when making a diagnosis. Whereas the ICD ignores other
factors and provides emphasis on first rank symptoms during diagnosis.
Firstly the ICD classification system appears to offer some advantages
over the DSM as the symptoms are only needed to be present for a month
whereas the DSM requires 6 months. This could pose a problem as
sufferers have to live for 6 months without receiving diagnosis and
therefore treatment. This increases the chance of sufferers becoming a
risk to themselves and others. However some may argue that the ICD’s
short period of a month required for diagnosis could led to labelling
individuals as schizophrenic when their symptoms may be due to a short
phase or life events such as bereavement etc. This has been
demonstrated by Rosenhan’s study
The problems with the medical classification has been highlighted by
Rosenhan. He found that psychiatrists could not reliably distinguish
