The revised Green et al., Paranoid Thoughts Scale (R-GPTS): psychometric properties, severity ranges, and clinical cut-offs
<p><strong>Background</strong> 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 evalu...
| Main Authors: | , , , , , , , , , |
|---|---|
| Format: | Journal article |
| Language: | English |
| Published: |
Cambridge University Press
2019
|
| _version_ | 1797090040958943232 |
|---|---|
| author | Freeman, D Loe, B Kingdon, D Startup, H Molodynski, A Rosebrock, L Brown, P Sheaves, B Waite, F Bird, J |
| author_facet | Freeman, D Loe, B Kingdon, D Startup, H Molodynski, A Rosebrock, L Brown, P Sheaves, B Waite, F Bird, J |
| author_sort | Freeman, D |
| collection | OXFORD |
| description | <p><strong>Background</strong> 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.</p> <p><strong>Methods</strong> 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.</p> <p><strong>Results</strong> 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.</p> <p><strong>Conclusions</strong> 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.</p> |
| first_indexed | 2024-03-07T03:12:46Z |
| format | Journal article |
| id | oxford-uuid:b4c3aa7d-8fa0-44a4-8ec9-fffaa3ed7126 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T03:12:46Z |
| publishDate | 2019 |
| publisher | Cambridge University Press |
| record_format | dspace |
| spelling | oxford-uuid:b4c3aa7d-8fa0-44a4-8ec9-fffaa3ed71262022-03-27T04:28:37ZThe revised Green et al., Paranoid Thoughts Scale (R-GPTS): psychometric properties, severity ranges, and clinical cut-offsJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:b4c3aa7d-8fa0-44a4-8ec9-fffaa3ed7126EnglishSymplectic Elements at OxfordCambridge University Press2019Freeman, DLoe, BKingdon, DStartup, HMolodynski, ARosebrock, LBrown, PSheaves, BWaite, FBird, J<p><strong>Background</strong> 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.</p> <p><strong>Methods</strong> 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.</p> <p><strong>Results</strong> 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.</p> <p><strong>Conclusions</strong> 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.</p> |
| spellingShingle | Freeman, D Loe, B Kingdon, D Startup, H Molodynski, A Rosebrock, L Brown, P Sheaves, B Waite, F Bird, J The revised Green et al., Paranoid Thoughts Scale (R-GPTS): psychometric properties, severity ranges, and clinical cut-offs |
| title | The revised Green et al., Paranoid Thoughts Scale (R-GPTS): psychometric properties, severity ranges, and clinical cut-offs |
| title_full | The revised Green et al., Paranoid Thoughts Scale (R-GPTS): psychometric properties, severity ranges, and clinical cut-offs |
| title_fullStr | The revised Green et al., Paranoid Thoughts Scale (R-GPTS): psychometric properties, severity ranges, and clinical cut-offs |
| title_full_unstemmed | The revised Green et al., Paranoid Thoughts Scale (R-GPTS): psychometric properties, severity ranges, and clinical cut-offs |
| title_short | The revised Green et al., Paranoid Thoughts Scale (R-GPTS): psychometric properties, severity ranges, and clinical cut-offs |
| title_sort | revised green et al paranoid thoughts scale r gpts psychometric properties severity ranges and clinical cut offs |
| work_keys_str_mv | AT freemand therevisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs AT loeb therevisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs AT kingdond therevisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs AT startuph therevisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs AT molodynskia therevisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs AT rosebrockl therevisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs AT brownp therevisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs AT sheavesb therevisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs AT waitef therevisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs AT birdj therevisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs AT freemand revisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs AT loeb revisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs AT kingdond revisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs AT startuph revisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs AT molodynskia revisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs AT rosebrockl revisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs AT brownp revisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs AT sheavesb revisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs AT waitef revisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs AT birdj revisedgreenetalparanoidthoughtsscalergptspsychometricpropertiesseverityrangesandclinicalcutoffs |