PHONE-BASED ASSESSMENT OF THE INCAT DISABILITY SCALE IN CHRONIC INFLAMMATORY DEMYELINATING POLYRADICULONEUROPATHY(CIDP) - ASPECTS OF VALIDITY AND RELIABILITY, AND CONGRUENCE WITH SITE-BASED ASSESSMENT
Author(s)
Guillaume Montagu, MSc1, Hilary Byrnes, PhD2, Christiane Otto, PhD3, Mattea Orsini, PhD4, Miguel Alonso Alonso, MD, PhD5, Mark Stettner, MD, PhD6, Jérôme Msihid, MSc1.
1Sanofi, Gentilly, France, 2ICON plc, Blue Bell, Niskayuna, NY, USA, 3ICON plc, Frankfurt, Germany, 4Aixial Group, Sèvres, France, 5Sanofi, Cambridge, MA, USA, 6University of Duisburg, Essen, Germany.
1Sanofi, Gentilly, France, 2ICON plc, Blue Bell, Niskayuna, NY, USA, 3ICON plc, Frankfurt, Germany, 4Aixial Group, Sèvres, France, 5Sanofi, Cambridge, MA, USA, 6University of Duisburg, Essen, Germany.
OBJECTIVES: The Inflammatory Neuropathy Cause and Treatment (INCAT) Disability Scale is a clinician-reported outcome (ClinRO) widely used in CIDP trials to assess arm and leg disability (total score 0-10). While traditionally administered in-person, remote assessment modalities may reduce patient and rater burden. This study aimed to investigate aspects of validity and reliability of the phone-based INCAT assessment using interim data of a Phase 2, proof-of-concept study evaluating riliprubart in adults with CIDP (NCT04658472).
METHODS: Both site- and phone-based INCAT assessments were conducted at six timepoints (Days 1-162). Psychometric analyses investigated floor/ceiling effects, inter-item correlations, and congruence with site-based assessments (Intraclass Correlation Coefficients; ICC). Analyses were performed in the overall sample and subgroups: Standard of Care (SOC) Naïve, SOC-Treated, and SOC-Refractory.
RESULTS: Overall, 64 patients were enrolled (11 SOC-Naïve, 19 SOC-Refractory, and 34 SOC-Treated).
For phone-assessed INCAT items, no floor (worst category) effects were observed at any timepoint; ceiling effects emerged at late timepoints, predominantly in the SOC-Treated subgroup, reflecting patient improvement and mirrored patterns observed in site-based assessments.
Inter-item correlations for phone-based assessments were mostly within the 0.2-0.4 benchmark; the Day 1 exception (r=0.61) was likely attributable to a very small sample size (N=15, 76.6% missing data).
Congruence between site and phone-based assessments was very good to excellent across all timepoints (ICC range: 0.95-0.99), with minimal mean score differences (range: −0.05 to +0.20).
Each group showed scores aligned with their clinical state (according to the Physician’s Global Assessment of Severity of CIDP), confirming known-groups validity.
CONCLUSIONS: Phone-administered INCAT demonstrated strong psychometric properties and very good to excellent congruence with site-based assessment in CIDP patients. Ceiling effects at late timepoints may limit sensitivity to change at lower disability levels. These findings support the validity and reliability of remote INCAT administration, offering the opportunity to reduce patient and rater burden.
METHODS: Both site- and phone-based INCAT assessments were conducted at six timepoints (Days 1-162). Psychometric analyses investigated floor/ceiling effects, inter-item correlations, and congruence with site-based assessments (Intraclass Correlation Coefficients; ICC). Analyses were performed in the overall sample and subgroups: Standard of Care (SOC) Naïve, SOC-Treated, and SOC-Refractory.
RESULTS: Overall, 64 patients were enrolled (11 SOC-Naïve, 19 SOC-Refractory, and 34 SOC-Treated).
For phone-assessed INCAT items, no floor (worst category) effects were observed at any timepoint; ceiling effects emerged at late timepoints, predominantly in the SOC-Treated subgroup, reflecting patient improvement and mirrored patterns observed in site-based assessments.
Inter-item correlations for phone-based assessments were mostly within the 0.2-0.4 benchmark; the Day 1 exception (r=0.61) was likely attributable to a very small sample size (N=15, 76.6% missing data).
Congruence between site and phone-based assessments was very good to excellent across all timepoints (ICC range: 0.95-0.99), with minimal mean score differences (range: −0.05 to +0.20).
Each group showed scores aligned with their clinical state (according to the Physician’s Global Assessment of Severity of CIDP), confirming known-groups validity.
CONCLUSIONS: Phone-administered INCAT demonstrated strong psychometric properties and very good to excellent congruence with site-based assessment in CIDP patients. Ceiling effects at late timepoints may limit sensitivity to change at lower disability levels. These findings support the validity and reliability of remote INCAT administration, offering the opportunity to reduce patient and rater burden.
Conference/Value in Health Info
2026-11, ISPOR Europe 2026, Vienna, Austria
Value in Health, Volume 29, Issue 12S
Code
CO14
Topic
Clinical Outcomes
Topic Subcategory
Clinician Reported Outcomes
Disease
Neurological Disorders, No Additional Disease & Conditions/Specialized Treatment Areas