By Mark Cowen, Senior medwireNews Reporter
The Community Assessment of Psychic Experience (CAPE) questionnaire is an effective instrument for identifying individuals at ultra-high risk (UHR) for psychosis, researchers report.
The CAPE "represents a useful screening tool for calling clinicians' attention to subjects with psychotic-like experiences and consequently detecting previously undiagnosed but help-seeking individuals," say Nilufar Mossaheb (Medical University Vienna, Austria) and team.
The availability of a screening tool to facilitate early detection in low-threshold, non-specialized settings is important as early treatment in schizophrenia and other psychoses is associated with better outcomes, they add.
The CAPE is a 42-item questionnaire covering positive, depressive, and negative symptom dimensions using two 4-point Likert scales: one to indicate frequency and one to indicate distress of symptoms.
To investigate whether the CAPE is an effective tool for detecting individuals at an increased risk for developing psychosis in a clinical, help-seeking population, the team studied 165 individuals, aged between 13 and 24 years, who were referred to an outpatient clinic for early detection and intervention in psychosis.
The utility of the CAPE questionnaire was assessed against the Comprehensive Assessment of At-Risk Mental States Interview (CAARMS) - a well-established instrument to classify individuals at UHR for psychosis.
In total, 84 (50.9%) patients were CAARMS-positive and 81 (49.1%) were CAARMS-negative for being at UHR for psychosis.
The positive predictive value of the entire test regarding a CAARMS-positive status was 65%, the negative predictive value was 63%, and sensitivity and specificity were both 64%.
Receiver operating characteristic curves were constructed for total CAPE score and the three dimension scores, and the area under the curve was almost identical for all. However, the curve of the positive symptom dimension underwent further analysis because such symptoms provide the basis for inclusion diagnoses in the CAARMS, say the researchers.
The team identified two suitable cut-off points at 3.20 and 2.80. The cut-off value of 3.20 showed a sensitivity of 67%, a specificity of 73%, a positive predictive value of 72% and a negative predictive value of 68%. The cut-off value of 2.80 showed a higher sensitivity (83%) and a better negative predictive value (74%), but a lower specificity (49%) and a reduced positive predictive value (63%).
Mossaheb et al conclude in Schizophrenia Research: "Our results show promise that the CAPE is a valid, simple and cost-effective instrument for detecting individuals at UHR in a clinical population."
They add: "With two different need-based cut-off points the CAPE can be used in settings with different prevalence rates of psychotic disorder and at-risk mental-state."
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