Grip Strength in CIDP: A Practical, Scalable Biomarker for Efficacy and Care Optimization

This content was created independently by NeurologyLive, with support by argenx.

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an autoimmune process without a clear autoantibody repertoire. It is hallmarked by progressive motor and sensory deficits. The majority of CIDP cases are thought to be evidenced by symmetric proximal and distal weakness involving the upper and lower limbs that is either progressive or relapsing; however, atypical forms of CIDP can occur. Disease heterogeneity can make diagnosis challenging. The diagnosis of CIDP is usually established by electrodiagnostic testing (electromyography/nerve conduction studies) and may also involve serological and cerebrospinal fluid analyses. It is prudent to solidify the diagnosis of CIDP before initiating therapy so that unnecessary exposure to therapeutic interventions does not occur. As such, consultation with neuromuscular experts is usually part of the diagnostic process.

Given the potentially progressive nature of CIDP, clinicians often rely on clinical examination alongside composite disability scores (Inflammatory Neuropathy Cause and Treatment [INCAT], Inflammatory Rasch-built Overall Disability Scale [I-RODS]) to track function. Handheld dynamometry adds a quantitative lens to motor performance that is quick, reproducible, and feasible at scale. I have found it to be useful in my clinical practice.^1,2 In fact, in the IVIg Immune Globulin Intravenous CIDP Efficacy analysis, grip strength detected clinically meaningful improvement earlier than INCAT—as soon as day 16—and identified more responders (37.5%-50.9% vs 21.1%-25.9% on placebo), establishing its sensitivity to treatment effects.³

Grip strength is an objective means to complement disability scales by quantifying motor output, while INCAT and I-RODS integrate upper- and lower-limb function, gait, and activities of daily living as patient-reported outcome measures.^1,2 It is reliable, actionable, and well-aligned with functional outcomes, which I have found to be particularly useful in my practice model.⁴ To reduce variability, the best practice for the use of grip strength analysis in practice suggests averaging values over 3 measurements. Numerically, the literature suggests greater than or equal to 8 kPa (vigorimeter) or greater than or equal to 10% lb Jamar as a marker for meaningful clinical improvement as evidenced across clinical trials.^1,4

As it pertains to treatment interventions, before the establishment of FcRn inhibition being effective in the treatment of CIDP, primary therapeutic approaches focused on initiation of IVIg or subcutaneous Ig therapy.Wear-off near the end of IVIg cycles can challenge disease stability. The multicenter IVIg treatment-related fluctuations (TRF) in CIDP patients using daily grip strength measurements (GRIPPER) study prospectively captured daily home grip strength for 6 months and found that approximately 50% of patients had 10% or more fluctuations that correlated with disability. These data enforce the importance of evidence-based optimization involving dose and frequency without waiting for overt clinical decline. Further, they provide evidence suggesting that following TRFs does not predict long-term disease activity and disability progression.^4-6 The ability to incorporate grip strength analysis easily into clinical practice has the potential to allow for a more individualized approach to IVIg scheduling, thereby avoiding overtreatment or undertreatment. I have found this to be particularly useful in my practice and have used grip strength measurements in the context of treatment-related fluctuations to specifically taper or adjust my patients’ IVIg dosing.

Novel therapies, like FcRn inhibition, have recently been incorporated into our CIDP treatment arsenal. FcRn inhibitors prevent the normal recycling mechanism that the IgG class of antibodies utilizes thereby reducing the quantity of all circulating IgG including those that are pathogenic. Those trials have embraced grip strength as a co‒primary or key response metric. In the phase 3 ADHERE trial, efgartigimod alfa and hyaluronidase-qvfc (Vyvgart hytrulo; argenx US Inc) demonstrated clinically meaningful improvements in strength and function for adults with CIDP, with grip strength serving as a predefined, objective marker of response. During stage A of the study, patients received weekly treatment for up to 12 weeks, and clinical improvement was confirmed when participants met responder criteria at 2 consecutive visits, defined by an INCAT improvement of 1 or more points, an I‑RODS improvement of 4 or more points, or a mean grip‑strength increase of at least 8 kPa. This threshold was also independently verified in the Veterans Affairs monograph, which specified that patients demonstrating isolated worsening in grip strength during run‑in could qualify as responders if they achieved an improvement of at least 8 kPa during treatment. Overall, 69% of participants met these response criteria and proceeded into the randomized withdrawal stage, underscoring the sensitivity of grip strength as an early, quantifiable indicator of therapeutic benefit with efgartigimod alfa and hyaluronidase-qvfc.^7,8 In the randomized withdrawal stage, Efgartigimod alfa and hyaluronidase-qvfc reduced the risk of relapse by 61% vs placebo (HR, 0.39; P = .000039), positioning grip strength within a robust efficacy framework and aligning mechanistic IgG lowering with functional motor gains.^7,8 This trial structure—responsive motor measure plus disability end point—mirrors what I anticipate we will see in future CIDP clinical trials—that establishment of disease modification via pharmacologic intervention can be guided by objective outcomes.⁷

Implementation in Practice

• Standardize measurement: Train patients on Jamar/vigorimeter technique; average 3 trials, track both hands, and document percent change or kPa delta.^1,4
• Define meaningful change: Use greater than or equal to 10% (lb Jamar) or greater than or equal to 8 kPa (vigorimeter) as practical thresholds, ideally averaged over 3 days.^1,4
• Integrate with visits: Capture baseline, pre/postinfusion/injection, and weekly home data to visualize wear‑off, then adjust interval/dose proactively.^4,5
• Embed in therapy transitions: Maintain grip strength logging to corroborate disability scale movement and confirm durability.^7-9

Grip strength changes can occur within weeks of initiating therapy, enabling faster confirmation of therapeutic benefit in a disease state that is hallmarked by heterogeneity. It is a meaningful, objective, and scalable outcome—responsive enough to detect early treatment benefit, practical for home monitoring of TRFs, and sufficiently validated to anchor response definitions in pivotal trials. Used alongside INCAT and I‑RODS, it improves signal clarity in both evidence generation and everyday CIDP care.

REFERENCES
1. Vanhoutte EK, Latov N, Deng C, et al. Vigorimeter grip strength in CIDP: a responsive tool that rapidly measures the effect of IVIG—the ICE study. Eur J Neurol. 2013;20(5):748-755. doi:10.1111/j.1468-1331.2012.03851.x
2. Allen JA, Gelinas DF, Lewis RA, Nowak RJ, Wolfe GI. Optimizing the use of outcome measures in chronic inflammatory demyelinating polyneuropathy. Eur Neurol Rev. . 2017;13(1):26-33. Accessed February 9, 2026. https://experts.umn.edu/en/publications/optimizing-the-use-of-outcome-measures-in-chronic-inflammatory-de/
3. Hughes RAC, Donofrio P, Bril V, et al; ICE Study Group. Intravenous immune globulin (10% caprylate-chromatography purified) for the treatment of chronic inflammatory demyelinating polyradiculoneuropathy (ICE study): a randomised placebo-controlled trial. Lancet Neurol. 2008;7(2):136-144. doi:10.1016/S1474-4422(07)70329-0
4. Allen JA, Pasnoor M, Dimachkie MM, et al. Quantifying treatment-related fluctuations in CIDP: results of the GRIPPER study. Neurology. 2021;96(14):e1876-e1886. doi:10.1212/WNL.0000000000011703
5. Kokubun N, Sada T, Yuki N, Okabe M, Hirata Kl. Optimization of intravenous immunoglobulin in chronic inflammatory demyelinating polyneuropathy evaluated by grip strength measurement. Eur Neurol. 2013;70(1-2):65-69. doi:10.1159/000350287
6. NewYork-Presbyterian Advances. CIDP: gaining insight on treatment-related fluctuations. December 27, 2022. Accessed February 9, 2026. https://www.nyp.org/advances/article/neurology-neurosurgery/cidp-gaining-insight-on-treatment-related-fluctuations
7. Allen JA, Lin J, Basta I, et al; ADHERE Study Group. Safety, tolerability, and efficacy of subcutaneous efgartigimod in patients with chronic inflammatory demyelinating polyradiculoneuropathy (ADHERE): a multicentre, randomised-withdrawal, double-blind, placebo-controlled, phase 2 trial. Lancet Neurol. 2024;23(10):1013-1024. doi:10.1016/S1474-4422(24)00309-0
8. Vyvgart hytrulo HCP site: ADHERE stage A response criteria (≥8 kPa grip). October 2025. Accessed February 9, 2026. https://vyvgarthcp.com/vyvgarthytrulo-cidp/clinical-data
9. Lünemann JD. Moving beyond immunoglobulin therapy for CIDP with efgartigimod. Nat Rev Neurol. 2025;21(1):1-2. doi:10.1038/s41582-024-01045-8

Disclosures

Consulting and advising efforts for:
Alexion, Amgen, Argenx, EMD Serono, Genentech, Johnson & Johnson, UCB