Patient outcome data exist, but standardization is still needed to better track and manage CIDP1
Many measures exist to quantify chronic inflammatory demyelinating polyneuropathy (CIDP) in academic and clinical settings. Yet a wide variation in how outcomes are measured remains, which complicates efforts to standardize disease monitoring.1
The Overall Neuropathy Limitations Scale (ONLS) and Vigorimeter-measured grip strength were used in CIDP clinical trials, alongside the commonly used outcome measures highlighted below.1
INCAT (Inflammatory Polyneuropathy Cause and Treatment) disability score, a 10-point scale used to measure activity limitation. The INCAT score for CIDP is the single most frequently reported clinical outcome assessment (COA) in the literature, appearing in 45.6% of publications.* INCAT is a disease-specific measure, which gives it relevance to the clinical characteristics of CIDP.1,2
Medical Research Council Scale for Muscle Strength (MRC) sum score, an assessment tool used to measure muscle strength by grading the 6 muscle groups on both sides of the body. MRC sum score interpretation in CIDP focuses on quantifying changes in proximal and distal muscle strength, and it is valued for its ease of use, consistency, and practicality to administer.1,3
I-RODS (Inflammatory Rasch-built Overall Disability Scale), a patient-reported outcome (PRO) measure used to assess activity and social participation limitations. As a disease-specific PRO, the I-RODS score in CIDP captures the patient perspective on functional limitations in a way that clinician-reported tools may not fully show.2
ONLS (Overall Neuropathy Limitations Scale), a 12-point scale used to measure limb function, where 0 indicates no disability and 12 reflects maximum disability. The ONLS was adapted from the Overall Disability Sum Score to better capture functional limitations such as the ability to run or use stairs, making it more sensitive to the mobility challenges seen in CIDP.4
mRS (Modified Rankin Scale), a simplified 6-grade assessment of neurologic disability originally developed for stroke patients and now applied in conditions such as CIDP. The mRS provides a broad measure of functional independence, offering clinicians a straightforward tool to track disability across a wide spectrum of disease severity.1,5
Vigorimeter-measured grip strength, an objective measure of hand muscle function used to augment broader scales like the MRC sum score. Because grip strength testing is particularly sensitive to the small muscle dysfunction common in peripheral neuropathies, it provides added precision in capturing the distal weakness characteristic of CIDP.6
These assessments are frequently used by healthcare providers with patient input or participation as treatment response markers, potentially influencing therapeutic decisions.1
The concept of minimal clinically important difference (MCID) defines what constitutes a meaningful change for patients. However, approaches for setting MCID thresholds depend on patient-centered tools, like the Patient Global Impression of Change, which are still underused in CIDP research. This gap limits both the ability to measure how patients experience their disease and the accuracy of determining what level of change truly matters to them.1
Standardized patient outcome benchmarks are needed1,7
The GBS/CIDP Foundation International Leadership Collaborative recently proposed standardized definitions for disease activity that incorporate patient perception of change alongside objective measures, including immune neuropathy–evidence of disease activity (IN-EDA) and immune polyneuropathy–no evidence of disease activity (IN-NEDA).
These consensus-based definitions were developed to facilitate consistent use of disease activity definitions across patient care and clinical research and to support broader stakeholder acceptance.
IN-EDA7
Patient perception of change AND actual change in disability, impairment, or both. There must be no other condition that better explains the change in disability and impairment.
IN-NEDA 17
No patient perception of change AND either no decline in disability OR no decline in impairment for a duration of 6 months or more.
IN-NEDA 27
No patient perception of change AND no decline in disability AND no decline in impairment for a duration of 6 months or more.
IN-EDA and IN-NEDA definitions were developed by a group organized by the GBS/CIDP Foundation International Leadership Collaborative. The supporting white paper is currently unpublished; definitions are subject to revision as consensus evolves.7
Additionally, the GBS/CIDP Foundation has proposed treatment response categories
These include:
Response, minimal7
Patient perception of improvement AND a minimum change (as defined in the IN-EDA definition) in at least 1 outcome measure suggesting at least early partial response to a specific treatment, assessed within 12 weeks.
Response, partial7
Patient perception of improvement AND a change in at least 1 outcome measure that reaches a higher change threshold (compared to minimal response) within 24 weeks. To meet the definition of partial response: a change of I-RODS of 8 centile points, MRC sum score of 4 points, or grip strength of 14 kPa is needed. A change in INCAT remains at 1 or more points.
Response, optimal7
Recovery as close as possible to the pre-CIDP functional status excluding potential residuals and fulfilling IN-NEDA 2 criteria sustained for at least 6 months.
Relapse7
Patient perception of change AND decline in disability AND impairment fulfilling IN-EDA definition following a period of stability or improvement, without a condition that better explains change in function and impairment, over a period of 12 weeks or less.
Refractory7
Absence of minimal response OR relapse leading to/requiring treatment discontinuation after adequate dosing and duration of the administered therapy.
Remission7
No signs of disease activity (IN-NEDA 2) with or without residuals without immunosuppressive/immunomodulatory therapy for at least 12 months.
Residuals7
Signs, symptoms, or impairments related to CIDP persist despite adequate immunosuppressive/immunomodulatory therapies and are present in a patient who otherwise has no evidence of disease activity (IN-NEDA).
Why patient outcome benchmarks matter8†
Real-world evidence highlights the need for continued focus on ambitious targets, including:
Improved clinical trials
Multidisciplinary management
Optimizing management
Identifying patients who do not respond to treatment
Although validated outcome measures exist for CIDP, consistent and repeated use of these measures is needed to enable more accurate, longitudinal evaluation of treatment response. Standardized, serial assessments may better capture disease trajectory over time, informing critical treatment decisions, including the need to switch therapies.1,8-11
*A review of CIDP literature published between 2010 and 2023, identifying 99 different COAs across 511 publications.1
†Data are drawn from the Adelphi Real World CIDP Disease Specific Programme™, a cross-sectional survey with retrospective data collection conducted between September 2022 and April 2023 across 8 countries. Patient-reported outcomes were collected from 428 of 1056 patients (40.5%) at the time of their clinic visit. Maintenance therapy was prescribed for 81.6% of patients in the overall cohort. Limitations may have included selection bias due to the voluntary nature of the survey, potential overrepresentation of more severe patients actively consulting physicians, and the cross-sectional study design, which did not allow causal conclusions.8
References: 1. Rajabally YA, Boggia GM, Riley D, et al. J Neurol Sci. 2025;477:123654. doi:10.1016/j.jns.2025.123654 2. Merkies ISJ, van Schaik IN, Bril V, et al. J Peripher Nerv Syst. 2022;27(2):159-165. doi:10.1111/jns.12487 3. Turan Z, Topaloglu M, Taskiran OO. Crit Care. 2020;24(1):562. doi:10.1186/s13054-020-03282-x 4. Graham RC, Hughes RAC. J Neurol Neurosurg Psychiatry. 2006;77(8):973-976. doi:10.1136/jnnp.2005.081547 5. van Swieten JC, Koudstaal PJ, Visser MC, Schouten HJA, van Gijn J. Stroke. 1988;19(5):604-607. doi:10.1161/01.str.19.5.604 6. Merkies ISJ, Schmitz PIM, Samijn JPA, van der Meché FGA, Toyka KV, van Doorn PA; for the Inflammatory Neuropathy Cause and Treatment (INCAT) Group. Muscle Nerve. 2000;23(9):1393-1401. doi:10.1002/1097-4598(200009)23:9<1393:AID-MUS10>3.0.CO;2-O 7. GBS|CIDP Leadership Collaborative. GBS|CIDP Leadership Collaborative Workshop. GBS|CIDP Foundation International. Accessed June 3, 2026. https://www.gbs-cidp.org/gbscidp-leadership-collaborative/ 8. Querol L, Rinaldi S, Borsi A, et al. J Peripher Nerv Syst. 2025;30(3):e70047. doi:10.1111/jns.70047 9. Rajabally YA, Ouaja R, Kasiborski F, Pujol S, Nobile-Orazio E. Muscle Nerve. 2022;66(5):562-567. doi:10.1002/mus.27713 10. Allen JA. Neurol Ther. 2020;9(1):43-54. doi:10.1007/s40120-020-00184-6 11. Yoon MS, Chan A, Gold R. Ther Adv Neurol Disord. 2011;4(3):193-200. 12. Schumacher A, Hieke A, Spenner M, et al. J Neurol. 2025;272(1):100. doi:10.1007/s00415-024-12860-w