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The psychometric properties of PSYCHLOPS, an individualized patient‐reported outcome measure of personal distress

Research output: Contribution to journalArticlepeer-review

Celia Sales, Luis Faísca, Mark Ashworth, Salma Ayis

Original languageEnglish
JournalJournal of Clinical Psychology
Early online date20 Nov 2021
DOIs
Accepted/In press27 Oct 2021
E-pub ahead of print20 Nov 2021

Bibliographical note

Funding Information: Salma Ayis is supported by funding from the National Institute for Health Research (NIHR) Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR, or the Department of Health. The other authors declare no external funding. Publisher Copyright: © 2021 Wiley Periodicals LLC

King's Authors

Abstract

Objective
Few studies report the psychometric properties of individualized patient-reported outcome measures (I-PROMs) combining traditional analysis and Item Response Theory (IRT).

Methods
Pre- and posttreatment PSYCHLOPS data derived from six clinical samples (n = 939) were analyzed for validity, reliability, and responsiveness; caseness cutoffs and reliable change index were calculated. Exploratory and confirmatory factor analyses were used to determine whether items represented a unidimensional construct; IRT examined item properties of this construct.

Results
Values for internal consistency, construct validity, convergent and discriminant validity, and structural validity were satisfactory. Responsiveness was high: Cohen's d, 1.48. Caseness cutoff and reliable clinical change scores were 6.41 and 4.63, respectively. IRT analysis confirmed that item scores possess strong properties in assessing the underlying trait measured by PSYCHLOPS.

Conclusion
PSYCHLOPS met the criteria for norm-referenced measurement of patient psychological distress. PSYCHLOPS functioned as a measure of a single latent trait, which we describe as “personal distress.”

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