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Data show accuracy of risk calculator for conversion to psychosis

Recent findings indicated accuracy of a risk calculator for individual risk for conversion to psychosis among clinical high-risk individuals.

“Given limitations of available treatments for schizophrenia, with most patients showing substantial deficits in social and occupational functioning throughout life, there is considerable interest in developing preventive approaches to psychotic disorders,” Tyrone D. Cannon, PhD, of Yale University, New Haven, Connecticut, and colleagues wrote. “Although clinical high-risk criteria have been validated in epidemiological studies as sensitive to conversion risk, their utility in individual decision making is currently limited, given that 65% to 80% of cases ascertained by these methods do not convert to psychosis within a 2-year time frame.”

To develop a risk calculator that determines probability of conversion to psychosis, researchers evaluated 596 clinical high-risk study participants from the second phase of the North American Prodrome Longitudinal Study (NAPLS-2) who were followed to time of conversion to psychosis or last contact. Predictors were chosen a priori based on a literature review on psychosis risk prediction in clinical high-risk cohorts.

Two-year probability of conversion to psychosis was 16%.

Higher levels of unusual thought content and suspiciousness, greater decline in social functioning, lower verbal learning and memory performance, slower processing speed, and younger age at baseline increased individual risk for psychosis.

Stressful life events, trauma and family history of schizophrenia were not significant predictors, according to researchers.

Multivariate analysis indicated a concordance index of 0.71.

Findings from Ricardo E. Carrión, PhD, of Zucker Hillside Hospital, Northwell Health, Glen Oaks, New York, and colleagues further confirmed accuracy among a sample of 210 study participants from the Early Detection, Intervention, and Prevention of Psychosis program.

An external validation model indicated an area under the receiver operating characteristic curve of 0.79 (95% CI, 0.644-0.937).

Further, individual risk generated by the risk calculator indicated a “solid estimation” of actual conversion in this validation sample, according to researchers.

“The data reported in this study have shown that the performance of the NAPLS-2 psychosis risk calculator, available on the Internet and incorporating a set of theoretically derived risk factors, can be replicated in a separate, independently collected clinical high-risk population. Although further replication is needed, at present the risk calculator appears to have considerable potential for determining the probability that an individual will develop psychosis, and it may provide a foundation for the personalized treatment of clinical high-risk individuals,” Carrión and colleagues concluded. – by Amanda Oldt

Disclosure: Cannon reports serving as a consultant for the Los Angeles County Department of Mental Health and Boehringer-Ingelheim Pharmaceuticals. Please see the full study for a list of all authors’ relevant financial disclosures.