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

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.

Medienart:

E-Artikel

Erscheinungsjahr:

2021

Erschienen:

2021

Enthalten in:

Zur Gesamtaufnahme - volume:51

Enthalten in:

Psychological medicine - 51(2021), 2 vom: 20. Jan., Seite 244-253

Sprache:

Englisch

Beteiligte Personen:

Freeman, Daniel [VerfasserIn]
Loe, Bao S [VerfasserIn]
Kingdon, David [VerfasserIn]
Startup, Helen [VerfasserIn]
Molodynski, Andrew [VerfasserIn]
Rosebrock, Laina [VerfasserIn]
Brown, Poppy [VerfasserIn]
Sheaves, Bryony [VerfasserIn]
Waite, Felicity [VerfasserIn]
Bird, Jessica C [VerfasserIn]

Links:

Volltext

Themen:

Assessment
Delusions
Journal Article
Paranoia
Research Support, Non-U.S. Gov't

Anmerkungen:

Date Completed 26.10.2021

Date Revised 29.01.2022

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1017/S0033291719003155

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM303475838