Minimal Clinically Important Differences in Measuring Treatment Effects in CIDP History, Current Use, Limitations, and Prospects
Abstract
Outcome measures are essential for evaluating treatment effects and disease progression in chronic inflammatory demyelinating polyneuropathy (CIDP). The concept of the minimal clinically important difference (MCID), which represents the smallest change in a measure deemed clinically meaningful, has become increasingly important in CIDP research, and is also gaining interest in clinical practice. This review explores the history of use in clinical trials and observational studies, as well as potential limitations and future perspectives for MCIDs in CIDP. MCID derivation methods include anchor-based approaches that rely on patient perspectives, and distribution-based methods that calculate the magnitude of changes exceeding statistical error margins. Both approaches have been used in CIDP, yielding MCID cut-offs for key scales such as the Inflammatory Neuropathy Cause and Treatment (INCAT) Scale, Overall Neuropathy Limitation Scale (ONLS), Rasch-built Overall Disability Scale (I-RODS), grip strength, and the Medical Research Council sum score. Challenges include discrepancies in MCID thresholds, particularly for I-RODS and strength measures, and variability related to disease severity and subtype. Despite these issues, MCIDs for disability measures such as INCAT, ONLS, and I-RODS have demonstrated their value through validity and clinical relevance, making them suitable for both research and clinical practice. MCIDs for strength scores, walking tests, sensory scales, and electrophysiological measures lack reliability and direct clinical relevance with regard to the primary concept of clinically meaningful benefit. Future research should focus on optimization of outcome measures, harmonization of MCID derivation methods, and exploration of MCID application with disease-specific Health Related-Quality of Life measures for CIDP.
Objectives:The objectives of this activity are to: (1) Understand the concept of minimal clinically important difference and how it is relevant for a variety of CIDP outcome measures; (2) be able to properly interpret MCID for various CIDP outcome measures in clinical practice; and (3) be able to properly interpret MCID for various CIDP outcome measures in clinical trials.
This paper underwent review by the Muscle & Nerve editor, but did not undergo additional, external peer review.
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DISCLOSURES
Dr. Zach Simmons (editor) has no conflicts of interest. Relevant financial relationships of the article’s authors have been disclosed and managed through the journal’s editorial review process.
Y.A.R. has received speaker/consultancy honoraria from Argenx, Sanofi, Grifols, Dianthus, Takeda, Johnson & Johnson, LFB, and Polyneuron; has received educational sponsorships from LFB and CSL Behring; and has obtained research grants from LFB. K.K.N. has received a research grant from LFB. The other author declares no conflicts of interest.
FORMATPDF
Yusuf A. Rajabally; Kabir K. Nazeer; Young Gi Min