biostudies-literatureJones ASKNational Institute for Health Research (NIHR)e122https://www.ebi.ac.uk/biostudies/studies/S-EPMC12094643biostudies-literatureUnknown55<h4>Background</h4>Individuals with long-term physical health conditions (LTCs) experience higher rates of depression and anxiety. Conventional self-report measures do not distinguish distress related to LTCs from primary mental health disorders. This difference is important as treatment protocols differ. We developed a transdiagnostic self-report measure of illness-related distress, applicable across LTCs.<h4>Methods</h4>The new Illness-Related Distress (IRD) scale was developed through thematic coding of interviews, systematic literature search, think-aloud interviews with patients and healthcare providers, and expert-consensus meetings. An internet sample (<i>n</i> = 1,398) of UK-based individuals with LTCs completed the IRD scale for psychometric analysis. We randomly split the sample (1:1) to conduct: (1) an exploratory factor analysis (EFA; <i>n</i> = 698) for item reduction, and (2) iterative confirmatory factor analysis (CFA; <i>n</i> = 700) and exploratory structural equation modeling (ESEM). Here, further item reduction took place to generate a final version. Measurement invariance, internal consistency, convergent, test-retest reliability, and clinical cut-points were assessed.<h4>Results</h4>EFA suggested a 2-factor structure for the IRD scale, subsequently confirmed by iteratively comparing unidimensional, lower order, and bifactor CFAs and ESEMs. A lower-order correlated 2-factor CFA model (two 7-item subscales: <i>intrapersonal</i> distress and <i>interpersonal</i> distress) was favored and was structurally invariant for gender. Subscales demonstrated excellent internal consistency, very good test-retest reliability, and good convergent validity. Clinical cut points were identified (<i>intrapersonal</i> = 15, <i>interpersonal</i> = 12).<h4>Conclusion</h4>The IRD scale is the first measure that captures transdiagnostic distress. It may aid assessment within clinical practice and research related to psychological adjustment and distress in LTCs.Psychological medicineThe Illness-Related Distress Scale: development and psychometric evaluation of a new transdiagnostic measure.PMC12094643NIHR203318Brown ADietz KCSeaton NWroe AHudson JLJones ASKMoss-Morris RJenkinson ECarroll SfalseThe Illness-Related Distress Scale: development and psychometric evaluation of a new transdiagnostic measure.<h4>Background</h4>Individuals with long-term physical health conditions (LTCs) experience higher rates of depression and anxiety. Conventional self-report measures do not distinguish distress related to LTCs from primary mental health disorders. This difference is important as treatment protocols differ. We developed a transdiagnostic self-report measure of illness-related distress, applicable across LTCs.<h4>Methods</h4>The new Illness-Related Distress (IRD) scale was developed through thematic coding of interviews, systematic literature search, think-aloud interviews with patients and healthcare providers, and expert-consensus meetings. An internet sample (<i>n</i> = 1,398) of UK-based individuals with LTCs completed the IRD scale for psychometric analysis. We randomly split the sample (1:1) to conduct: (1) an exploratory factor analysis (EFA; <i>n</i> = 698) for item reduction, and (2) iterative confirmatory factor analysis (CFA; <i>n</i> = 700) and exploratory structural equation modeling (ESEM). Here, further item reduction took place to generate a final version. Measurement invariance, internal consistency, convergent, test-retest reliability, and clinical cut-points were assessed.<h4>Results</h4>EFA suggested a 2-factor structure for the IRD scale, subsequently confirmed by iteratively comparing unidimensional, lower order, and bifactor CFAs and ESEMs. A lower-order correlated 2-factor CFA model (two 7-item subscales: <i>intrapersonal</i> distress and <i>interpersonal</i> distress) was favored and was structurally invariant for gender. Subscales demonstrated excellent internal consistency, very good test-retest reliability, and good convergent validity. Clinical cut points were identified (<i>intrapersonal</i> = 15, <i>interpersonal</i> = 12).<h4>Conclusion</h4>The IRD scale is the first measure that captures transdiagnostic distress. It may aid assessment within clinical practice and research related to psychological adjustment and distress in LTCs.2025-01-01T00:00:00Z2025 Apr2026-06-02T17:54:58.923Z2026-04-18T03:12:18.486ZS-EPMC120946434028964310.1017/S003329172500090X