Minimal important differences and self‐identifying treatment response in chronic inflammatory demyelinating polyneuropathy

Yusuf A. Rajabally, Saadia Afzal, Majid Ghasemi

Research output: Contribution to journalArticlepeer-review


Introduction/Aim: The use of outcome measures is recommended for chronic inflammatory demyelinating polyneuropathy (CIDP). Implications of minimal important differences (MID) to ascertain responder status are unknown. The reliability of patient-reported treatment-response in relation to clinically relevant change is also unknown. Methods: We retrospectively studied 72 subjects with “definite” or “probable” CIDP evaluated at pre-specified time-intervals pre- and post-treatment. We derived MID and the minimum detectable change with 95% confidence intervals (MDC95) for four scales. Scale sensitivities were determined with applicable MID-defined cutoffs (aMIDc), to detect subjects with self-identifying treatment response through a single question. Results: The use of MID was not valid for the Medical Research Council Sum Score, as MDC95 > MID. The aMIDc for the Overall Neuropathy Limitation Score (ONLS) was 1 (sensitivity: 84.7%). The aMIDc for the centile Inflammatory Rasch-built Overall Disability Scale (cI-RODS) was 8 (sensitivity: 62.3%). The aMIDc for grip strength was 4 kg (sensitivity: 79.1%). MID-defined amelioration of any one scale among ONLS, cI-RODS, or grip strength, significantly improved sensitivity to detect treatment-responders compared with the ONLS alone (McNemar test: P = .008, odds ratio: 3.36 [95% confidence interval: 1.44–7.86]). Patient-reported improvement was highly reliable in relation to MID-defined amelioration on any one scale. Discussion: In subjects with CIDP, MID-defined amelioration of any one of three commonly used outcome measures offers optimum relevance and sensitivity to detect self-identifying treatment-responders. Patient reliability to single-question ascertainment of response is high in relation to MID-defined clinical relevance. These findings support use of multiple outcome measures in CIDP monitoring and justify enhanced patient involvement in the process.
Original languageEnglish
Pages (from-to)37-42
Number of pages6
JournalMuscle and Nerve
Issue number1
Early online date9 Apr 2021
Publication statusPublished - Jul 2021


  • chronic inflammatory demyelinating polyneuropathy
  • minimum detectable change
  • minimum important difference
  • outcome measures
  • responders
  • self-identifying
  • sensitivity


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