Magazine article Clinical Psychiatry News

Risk Markers May Help Prevent Conversion to Psychosis

Magazine article Clinical Psychiatry News

Risk Markers May Help Prevent Conversion to Psychosis

Article excerpt


NEW YORK -- A combination of four readily available clinical and psychosocial tests can predict whether patients are at risk for converting to psychosis with fair to good positive predictive value, an investigator asserts.

Measures of thought content, suspiciousness, and subscales of the Brief Assessment of Cognition in Schizophrenia instrument, as well as total life events, can predict with fairly good sensitivity and specificity which patients will progress to psychosis, said Tyrone D. Cannon, Ph.D., professor of psychology and psychiatry at Yale University in New Haven, Conn.

"The foundation of any effective prevention program has to begin with the goal of prediction; we have to find the people most at risk. And then another pillar of prevention is understanding something about the underlying mechanisms of illness," he said at the American Psychiatric Association annual meeting.

The clinical high-risk (CHR) paradigm is based on the establishment of CHR criteria that can capture the population at risk of imminent onset of psychosis. A recent systematic review risk of CHR research (JAMA Psychiatry 2013;70:107-20) found that among high-risk patients, rates of conversion to psychosis were about 15% by 1 year of follow-up and 30% by 2 years. Of those who convert to psychosis, about 80% develop a schizophrenia spectrum disorder, and about 20% develop mood or atypical psychoses. A second study (Schizophr. Bull. 2012;38:1225-33) showed that of nonconverters, one-third recover symptomatically by 2 years, an additional third recover functionally, and another third recover both symptomatically and functionally.

Therefore, a good rule of thumb is that among CHR populations, about one-third will remit, one-third will convert to psychosis, and one-third will remain in a CHR state, Dr. Cannon said. Of the latter group, some might convert to schizophrenia or psychosis, and some might develop schizotypal disorders.

Currently available multivariate algorithms that involve specific combinations of symptoms and demographic factors generally have high positive predictive values and specificity but tend to have low sensitivity, and the accepted diagnostic profiles vary widely across different studies, he said.

Dr. Cannon and colleagues in the NAPLS (North American Prodrome Longitudinal Study) consortium have studied clinical predictors of psychosis in 360 of the 750 planned CHR patients recruited. Of this group, 60 converted to psychosis within 2 years, and the remaining nonconverters were followed for the same period.

The investigators examined the receiver operating characteristic (ROC) curves for predictive models for which there were 10 or more converters per predictor. …

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