Minimal important differences and self‐identifying treatment response in chronic inflammatory demyelinating polyneuropathy
Yusuf A. Rajabally, Saadia Afzal, Majid Ghasemi
Abstract
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: ) 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: > 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.