The revised Green et al., Paranoid Thoughts Scale (R-GPTS): psychometric properties, severity ranges, and clinical cut-offs

Abstract

Background The Green et al., Paranoid Thoughts Scale (GPTS) – comprising two 16-item scales assessing ideas of reference (Part A) and ideas of persecution (Part B) – was developed over a decade ago. Our aim was to conduct the first large-scale psychometric evaluation. Methods In total, 10 551 individuals provided GPTS data. Four hundred and twenty-two patients with psychosis and 805 non-clinical individuals completed GPTS Parts A and B. An additional 1743 patients with psychosis and 7581 non-clinical individuals completed GPTS Part B. Factor analysis, item response theory, and receiver operating characteristic analyses were conducted. Results The original two-factor structure of the GPTS had an inadequate model fit: Part A did not form a unidimensional scale and multiple items were locally dependant. A Revised-GPTS (R-GPTS) was formed, comprising eight-item ideas of reference and 10-item ideas of persecution subscales, which had an excellent model fit. All items in the new Reference (a = 2.09–3.67) and Persecution (a = 2.37–4.38) scales were strongly discriminative of shifts in paranoia and had high reliability across the spectrum of severity (a > 0.90). The R-GPTS score ranges are: average (Reference: 0–9; Persecution: 0–4); elevated (Reference: 10–15; Persecution: 5–10); moderately severe (Reference: 16–20; Persecution:11–17); severe (Reference: 21–24; Persecution: 18–27); and very severe (Reference: 25+; Persecution: 28+). Recommended cut-offs on the persecution scale are 11 to discriminate clinical levels of persecutory ideation and 18 for a likely persecutory delusion. Conclusions The psychometric evaluation indicated a need to improve the GPTS. The R-GPTS is a more precise measure, has excellent psychometric properties, and is recommended for future studies of paranoia.

Adherence to safety and self-isolation guidelines, conspiracy and paranoia-like beliefs during COVID-19 pandemic in Poland - associations and moderators

“…Green Paranoid Thoughts Scale-Revised (R-GPTS) - is a comprehensive questionnaire of paranoia-like beliefs to be used in clinical and general population settings ( Freeman et al, 2019 ). This study employed only the Reference subscale, consisting of 8 items, and with excellent internal consistency, α = 0.91.…”

Paranoia and belief updating during a crisis

“…Following task completion, questionnaires were administered via Qualtrics, we queried demographic information (age, gender, educational attainment, ethnicity, and race) and mental health questions (past or present diagnosis, medication use, Structured Clinical Interview for DSM-IV Axis II Personality Disorders (SCID-II) 8 , Beck’s Anxiety Inventory (BAI) 41 , Beck’s Depression Inventory (BDI) 42 , the Dimensional Obsessive-Compulsive Scale (DOCS) 19 , and critically, the revised Green et al, Paranoid Thoughts Scale (R-GPTS) 6 – dividing clinically from non-clinically paranoid individuals based on the ROC-recommended cut-off score of 11 – and an additional item pertaining to their beliefs about the social task (‘Did any of the partners deliberately sabotage you?’) – on a Likert scale from ‘Definitely not’ to ‘Definitely yes’.…”

“…Before the pandemic, people who were more paranoid (scoring in the clinical range on standard scales 6 , 8 ) were more likely to switch their choices between options, even following positive feedback 5 . We compared those data (gathered via the Amazon Mechanical Turk Marketplace in the U.S.A. between December 2017 and August 2018) to a new task version with identical contingencies, but framed socially ( Figure 1a ).…”

Treating sleep problems in young people at ultra-high-risk of psychosis: study protocol for a single-blind parallel group randomised controlled feasibility trial (SleepWell)

“…Sleep and activity levels will also be assessed using actigraphy (over 7 days), complemented with sleep diaries and a time-budget assessing meaningful activity. 35 Attenuated psychotic symptoms and transition to psychosis (Comprehensive Assessment of At-Risk-Mental-States (CAARMS) 30 ), hallucinatory experiences (Specific Psychotic Experiences Questionnaire -Hallucinations subscale (SPEQ-H) 36 ), paranoia (Revised-Green et al Paranoid Thoughts scale (R-GPTS) 37 ) and dissociative experiences (Černis Felt Sense of Anomaly Scale (ČEFSA) 38 ) will be assessed.…”