Psychometric Evaluation of the Immune Thrombocytopenic Purpura Patient Assessment Questionnaire Item-10 (Physical Fatigue) and Idiopathic Thrombocytopenic Purpura Bleeding Scale Using LUNA 3 Phase 3 Trial Data
Author(s)
Imene Gouia, PharmD1, Orsini Mattea, PhD2, Joshua Maher, PhD3, George Skingley, BSc4, Asha Lehane, MSc4, Helena Bradley, BSc4.
1HEVA, Rare Blood Diseases, Sanofi, Gentilly, France, 2Aixial Group, Sevres, France, 3Sanofi, Reading, United Kingdom, 4Adelphi Values, Bollington, United Kingdom.
1HEVA, Rare Blood Diseases, Sanofi, Gentilly, France, 2Aixial Group, Sevres, France, 3Sanofi, Reading, United Kingdom, 4Adelphi Values, Bollington, United Kingdom.
OBJECTIVES: This study evaluated the psychometric properties of Item-10 (physical fatigue) of the Immune Thrombocytopenia Purpura Patient Assessment Questionnaire (ITP-PAQ), and the Idiopathic Thrombocytopenic Purpura Bleeding Scale (IBLS) total score in the context of a phase 3 trial of rilzabrutinib in ITP (LUNA 3 trial), wherein these supported key secondary endpoints.
METHODS: Blinded data from the LUNA 3 phase 3 trial collected across timepoints (baseline to Week 25) were analysed for the intent-to-treat population. Psychometric evaluation assessed scores’ and items’ distributional properties, test-retest reliability, construct validity (convergent correlations and known-groups comparisons), and ability to detect change. The study also aimed to derive between-group meaningful score difference (MSD) thresholds used to define clinically meaningful change. The between-group MSD threshold was established using anchor-based methods and supported by distribution-based analysis.
RESULTS: Data from 202 patients were analysed. Test-retest reliability was good for ITP-PAQ Item-10 (κ=0.69-0.75) and moderate for IBLS total score (intra-class correlation coefficient =0.65-0.75). Convergent correlations were moderate-to-strong (>|0.40|) for ITP-PAQ Item-10 with Patient Global Impression of Severity (PGIS), and relevant EQ-5D items, and smaller (PGIS: r=0.36; EQ-5D visual analogue scale: r=0.24) for IBLS total score. Known-groups comparisons confirmed both scores' ability to discriminate between distinct severity levels. Larger within-group effect sizes for means of ‘improved’ compared to ‘stable’ participants supported ability to detect improvement for ITP-PAQ Item-10 and IBLS total score. The between-group MSD thresholds for ITP-PAQ Item-10 and IBLS total scores ranged from 8-18 points and 0.05-0.10 points, respectively.
CONCLUSIONS: The findings support the reliability, validity, and ability of ITP-PAQ Item-10 and IBLS total score to detect improvement, supporting their use as key secondary endpoints in clinical trials in ITP. The between-group MSD thresholds derived support interpretation of clinically meaningful improvement.
METHODS: Blinded data from the LUNA 3 phase 3 trial collected across timepoints (baseline to Week 25) were analysed for the intent-to-treat population. Psychometric evaluation assessed scores’ and items’ distributional properties, test-retest reliability, construct validity (convergent correlations and known-groups comparisons), and ability to detect change. The study also aimed to derive between-group meaningful score difference (MSD) thresholds used to define clinically meaningful change. The between-group MSD threshold was established using anchor-based methods and supported by distribution-based analysis.
RESULTS: Data from 202 patients were analysed. Test-retest reliability was good for ITP-PAQ Item-10 (κ=0.69-0.75) and moderate for IBLS total score (intra-class correlation coefficient =0.65-0.75). Convergent correlations were moderate-to-strong (>|0.40|) for ITP-PAQ Item-10 with Patient Global Impression of Severity (PGIS), and relevant EQ-5D items, and smaller (PGIS: r=0.36; EQ-5D visual analogue scale: r=0.24) for IBLS total score. Known-groups comparisons confirmed both scores' ability to discriminate between distinct severity levels. Larger within-group effect sizes for means of ‘improved’ compared to ‘stable’ participants supported ability to detect improvement for ITP-PAQ Item-10 and IBLS total score. The between-group MSD thresholds for ITP-PAQ Item-10 and IBLS total scores ranged from 8-18 points and 0.05-0.10 points, respectively.
CONCLUSIONS: The findings support the reliability, validity, and ability of ITP-PAQ Item-10 and IBLS total score to detect improvement, supporting their use as key secondary endpoints in clinical trials in ITP. The between-group MSD thresholds derived support interpretation of clinically meaningful improvement.
Conference/Value in Health Info
2025-11, ISPOR Europe 2025, Glasgow, Scotland
Value in Health, Volume 28, Issue S2
Code
MSR174
Topic
Methodological & Statistical Research
Topic Subcategory
PRO & Related Methods
Disease
Rare & Orphan Diseases, Systemic Disorders/Conditions (Anesthesia, Auto-Immune Disorders (n.e.c.), Hematological Disorders (non-oncologic), Pain)