Background
Longitudinal studies of the clinical high risk (CHR) syndrome for psychosis have emphasized the conversion vs non-conversion distinction and thus far have not focused intensively on classification among non-converters. The present study proposes a system for classifying CHR outcomes over time when using the Structured Interview for Psychosis-risk Syndromes and evaluates its validity.
Method
The system for classifying CHR outcomes is referred to as “current status specifiers,” with “current” meaning over the month prior to the present evaluation and “specifiers” indicating a set of labels and descriptions of the statuses. Specifiers for four current statuses are described: progression, persistence, partial remission, and full remission. Data from the North American Prodromal Longitudinal Study were employed to test convergent, discriminant, and predictive validity of the current status distinctions.
Results
Validity analyses partly supported current status distinctions. Social and role functioning were more impaired in progressive and persistent than in remitted patients, suggesting a degree of convergent validity. Agreement between CHR current statuses and current statuses for a different diagnostic construct (DSM-IV Major Depression) was poor, suggesting discriminant validity. The proportion converting to psychosis within a year was significantly higher in cases meeting progression criteria than in those meeting persistence criteria and tended to be higher than in those meeting full remission criteria, consistent with a degree of predictive validity.
Discussion
CHR syndrome current status specifiers could offer a potentially valid and useful description of current clinical status among non-converters. Study in additional samples is needed.
A prodromal period before the onset of frank schizophrenia has been recognized for at least a century (Bleuler, 1911 and Klosterkotter et al., 2008), and over the past two decades a growing body of work has sought to diagnose a prodromal syndrome prospectively (Fusar-Poli et al., 2013). One approach has been to define clinical high risk (CHR) criteria, also known as at-risk mental state or ultra-high risk or risk syndrome (Schultze-Lutter et al., 2011) criteria. Two structured diagnostic interviews, the Comprehensive Assessment of At Risk Mental States (CAARMS) (Yung et al., 2004) and the Structured Interview for Psychosis-risk Syndromes (SIPS) (McGlashan et al., 2010) have demonstrated reliability and validity (Yung et al., 2005, Addington et al., 2007, Yung et al., 2008, Woods et al., 2009, Woods et al., 2010 and Fusar-Poli et al., 2012b).
While CHR criteria consistently have been statistically significant predictors of conversion, it has become more clear over the past decade that the majority of patients meeting the criteria do not go on to become psychotic (Cannon et al., 2008, Ruhrmann et al., 2010, Fusar-Poli et al., 2012a and Nelson et al., 2013). Some of the non-converting patients remain symptomatic over time, and others become symptom-free (Addington et al., 2011). At present, however, existing diagnostic criteria have paid relatively little attention to follow-up classification.
This paper proposes a new classification system for CHR patients when using the SIPS over time. The system is based on diagnostic criteria that establish eligibility for classification and specifiers of current status that may vary over follow-up. Data from the first phase of the North American Prodrome Longitudinal Study (Addington et al., 2007) (NAPLS-1) are used to evaluate the validity of the current status distinctions.
