Inter-rater reliability of subthreshold psychotic symptoms in individuals with 22q11.2 deletion syndrome

Tyler M Moore,Raquel E Gur,Leila Kushan,Wendy R Kates,Ronnie Weinberger,Doron Gothelf,Monica E Calkins,Robert Sean Gallagher,Carrie E Bearden,Donna M Mcdonald-Mcginn,Dafna Sofrin Frumer,Deby Salzer

doi:10.1186/s11689-021-09372-3

Abstract

BackgroundPathways leading to psychosis in 22q11.2 deletion syndrome (22q11.2DS) have been the focus of intensive research during the last two decades. One of the common clinical risk factors for the evolution of psychosis in 22q11.2DS is the presence of positive and negative subthreshold psychotic symptoms. The gold standard for measuring subthreshold symptoms is the Structured Interview for Prodromal Syndromes (SIPS) and its accompanying Scale of Prodromal Symptoms (SOPS) ratings. Although the scale has been used by many centers studying 22q11.2DS, the inter-site reliability of the scale in this population has never been established.MethodsIn the present study, experienced clinical assessors from three large international centers studying 22q11.2DS independently rated video recordings of 18 adolescents and young adults with 22q11.2DS.ResultsThe intraclass correlations coefficients (ICCs) among three raters for the SOPS total scores, as well as for the positive, negative, and disorganization subscale scores, were good-to-excellent (ICCs range 0.73–0.93). The raters were also able to reliably determine the subjects’ subthreshold syndrome status (ICC = 0.71). The reliability of individual items was good-to-excellent for all items, ranging from 0.61 for motor disturbances [G3] to 0.95 for bizarre thinking.ConclusionsOur results show that trained clinicians can reliably screen for subthreshold psychotic symptoms in individuals with 22q11.2DS. To increase assessment reliability, we suggest specific clarifications and simplifications to the standard SIPS interview for future studies.

Highlights

Pathways leading to psychosis in 22q11.2 deletion syndrome (22q11.2DS) have been the focus of intensive research during the last two decades
Thirty-nine percent of the sample (n = 7) had no subthreshold psychotic symptoms, 33% had negative/disorganized symptoms (n = 6), 17% (n = 3) positive and positive + negative/disorganized subthreshold symptoms were present in two subjects (11%)
The lower rates were for the “general” items, which are of minor importance in the Structured Interview for Prodromal Syndromes (SIPS) interview as they are not part of the definition of clinical high risk state

Summary

Introduction

Pathways leading to psychosis in 22q11.2 deletion syndrome (22q11.2DS) have been the focus of intensive research during the last two decades. Schizophrenia is a neurodevelopmental disorder with a prodromal phase of milder symptoms, including disturbances in perception thought processes, with yet intact reality testing. These symptoms are considered “attenuated positive symptoms.”. The Structured Interview for Prodromal Symptoms (SIPS) was developed to objectively quantify the attenuated psychotic symptoms that are subthreshold and present in the clinical high risk (CHR) state [6]. Because psychotic disorders are prevalent in 22q11.2DS, research efforts are devoted to identifying early signs and predictors of psychosis in this population, leading to the study of attenuated psychotic symptoms in 22q11.2DS [8,9,10,11,12,13,14,15,16,17]

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