rater. Reliability was reasonably high overall, with 0.53
agreement when diagnosing using the DSM-III-R and
0.59 agreement when using ICD-10. Affective disorders
gave good agreement; there was moderate agreement
for schizophrenia, though for schizoaffective disorder
there was not enough reliability. It was thought that
schizoaffective disorder was not sufficiently separate
from schizophrenia and bipolar disorder. In order to be
diagnosed, schizophrenia must have had symptoms lasting
for six months in the DSM-III-R and lasting for one
month in the ICD-10, which affected frequency rates.
Therefore, there seems to be reliability when using both
classification systems but there are also some issues around
which diagnosis is made.
Cheniaux eta/. (2009)
- -'it seems that ICD-10, like the newer DSM
, v•ersimlS, gives reliability when it comes to diagnosis of
schizophrenia. As Lee (2005) has said, 'there are more
Sim..llarities than differences in diagnoses of schizophrenia'.
The following studies focus on the reliability ofiCD-10
and schizophrenia.
Jakobsen et a/. (2005)
Jakobsen et al. (2005) used a random sample ofDanish inpatients diagnosed with schizophrenia and a sample of
out-patients with a history of psychosis to look at the
reliability of the ICD-10 with regard to schizophrenia. An
ICD-10 diagnosis showed 93 per cent sensitivity and 87
per cent predictive value when it came to a diagnosis of
schizophrenia and showed good agreement between the
ICD-10 and diagnosis using another measure. Jakobsen
et al. (2005) concluded that the ICD-10 gave a reliable
diagnosis of schizophrenia.
Hiller eta/. (1992)
Hiller et al. (1992) compared the ICD-10 with the
DSM-III-R to look at their validity and reliability.
The researchers used both classification systems on the
same set of patients who were suffering from affective
(about feelings and emotions) and psychotic {not in
touch with reality) disorders. The ICD-10 gave higher
reliability for all the disorders looked at except for bipolar
disorder. Reliability was tested using more than one
Cheniaux et al. (2009) looked at various diagnoses,
including schizophrenia, bipolar depression and unipolar
depression. They used inter-rater reliability, as is usual
in such studies, and their aim was to look at reliability of
diagnosis using the DSM-IV and the ICD-10. Two trained
psychiatrists used interviewing to assess the diagnosis of
100 in-patients. They found that schizophrenia was more
frequent using the ICD-10 than if using the DSM-IV.
Only for schizoaffective disorder, which was also looked
at, did the reliability between the two classification systems
drop below 0.50. Bipolar disorder was the one most
reliably diagnosed.
Explanation
STUDY HINT
We have used the example of schizophrenia to explain the
need to focus on reliability and validity.The information
covered here on schizophrenia will also be useful when you
are learning about schizophrenia as part of your studies of
content in clinical psychology.
Validity of ICD-10 for schizophrenia
Pihlajamaa et al. (2008)
Pihlajamaa et al. (2008) looked at the validity of
schizophrenia diagnosis using the DSM-III-R, the
DSM-IV and the ICD-10 in order to compare them.
Their study looked at 877 people born in Helsinki in
Finland between 1951 and 1960 who had had at least one
diagnosis of schizophrenia, schizophreniform disorder or
schizoaffective disorder (core schizophrenia spectrum
diagnoses). Case notes were available for 807 of the people
identified and so they were the sample used.
The researchers used the case notes in the Finnish Hospital
Discharge Register to look at diagnoses according to the
Register as well as the three classification systems (the
DSM-III-R, the DSM-IV and the ICD-10) and compared
the diagnoses to look at their validity. Validity was said to
exist when individuals received the same diagnosis from
the different diagnostic systems as stated in the Register.
This study was about having more than one measure (the
diagnosis in the Register and the ones done separately
using the diagnostic classifications) to see if the diagnoses
matched. If they matched, that would mean they were
valid. Using the DSM-III-R diagnosis and the Register
diagnosis, individuals had the same diagnosis 75 per cent of
the time and using the ICD-10 diagnosis and the Register
diagnosis, they had the same diagnosis 78 per cent of the
time. This study looked at the core schizophrenia spectrum
diagnoses. Other validity figures, such as comparing
people with schizophrenia alone, or using the DSM-IV
and the Register, were also around 70 to 80 per cent. The
researchers concluded that generally, when taking
information from case studies in the Register, the Register
diagnosis and comparing them using the ICD-10 and the
DSM, it could be seen that diagnoses were valid. However,
they did find some issues if people had a diagnosis of both a
core schizophrenia spectrum disorder and bipolar I disorder.
G
EdexcelPsychology for A level Book 2
Core schizophrenia spectrum disorders come under
the spectrum of psychotic disorders, which includes
schizophrenia, schizoaffective disorder, delusional disorder,
schizotypal personality disorder, schizophreniform disorder,
brief psychotic disorder and some other psychoses linked to
substance misuse or medical conditions.
Jansson eta/. (2002)
Jansson et al. (2002) wanted to look at the ICD-10 criteria
for schizophrenia compared with other diagnostic systems.
They looked at concurrent validity of the ICD-9 and the
ICD-10, which means they wanted to see if the two would
yield the same diagnosis for the same individual at the same
moment in time. The researchers looked at 155 patients
in Copenhagen from 1998 to 2000. The sample included
psychotic patients and those that were non-psychotic but
seemed to be within the schizophrenia spectrum.
A large amount of data were gathered by interview, including
many different assessments, notes, interviews from second
informants, diagnostic criteria and family history. The
diagnoses were then compared to check the validity
of the different classification systems. The ICD-10 and the
DSM-IV gave the best diagnostic agreement (0.823).
However, the researchers reported differences in diagnoses
for individuals and some differences between diagnostic
systems, including between the ICD-9 and the ICD-10.
They thought that the boundaries for schizophrenia needed
redrawing as it was not clear exactly where the boundaries
were, given the amount of data they analysed and the
differences in diagnosis that were found.
The ICD-10 seems to be less valid than the ICD-9 in some
situations, which seems to be because the ICD-9 focuses on
features such as autism and self-dissolution whereas the
ICD-10 focuses more on noticeable psychotic phenomena
and negative symptoms. This study has a lot of complexity,
which is not reported here, but the basic point is that there
is validity in the diagnostic classification in general, but
when looking more at the detail there are differences.