Development and psychometric properties of
a semi-structured clinical interview for
psychosis sub-groups (SCIPS).
University of Southampton, School of Medicine,
Background: Schizophrenia has long been considered to be remarkably heterogeneous,
and there have been a number of attempts to identify sub-groups of this disorder which
are more homogeneous. Nevertheless, most of these have not been used in either research
or clinical practice to any great extent, because diagnoses by way of these strategies
would be unstable over time and impractical. In such circumstances, the vulnerabilitystress
model has led to the development of a new concept of sub-grouping schizophrenia
into 4 sub-types – drug related, traumatic, anxiety, and stress sensitivity. This
conceptualisation is quite promising, not only because it may provide stable and practical
diagnoses, but also because the terminology used therein is useful when it comes to
destigmatising those who are currently diagnosed with schizophrenia.
Methodology: In order to adapt this concept for practical use, this project set out to
develop a semi-structured interview for making diagnoses according to it. Thereafter,
psychometric properties of the interview were examined. This assessment tool was then
used to confirm the longitudinal stability of the diagnosis. In order to establish the
construct validity of this classification system, it was examined if the anxiety and stress
sensitivity sub-groups in this system were different in terms of their external validators.
Three psychopathological variables – evaluative belief, fear of negative evaluation from
others, and depression – were assessed in a cross-sectional study during this process of
validation. Three other clinical variables – two for the duration of hospitalization and one
for the risk of self harming – were also used in a retrospective cohort study for the
evaluation of the predictive value of the differentiation.
Results and conclusion: Both the English and Japanese versions of the semi-structured
clinical interview for psychosis sub-groups (SCIPS) were developed to sub-group
patients into 4 categories, and their reliability and concurrent validity were established.
The 6 month stability of SCIPS diagnoses of the drug related, anxiety and stress
sensitivity sub-types was also indicated through a longitudinal study. A preliminary
analysis provided little evidence of construct validity. The risk of self harming was,
however, suggested as being associated with a distinction between the anxiety and stress
sensitivity categories when the SCIPS was applied to a broader range of psychosis,
including schizophrenia and schizoaffective disorder.
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