Comparative value and determinants of suitability of outcome measures in treated chronic inflammatory demyelinating polyneuropathy

Abstract

Introduction: The comparative value and suitability of outcome measures are uncertain in chronic inflammatory demyelinating polyneuropathy (CIDP).  Methods: We studied 35 patients with CIDP using the Overall Neuropathy Limitation Scale (ONLS), the inflammatory Rasch-built Overall Disability Scale (I-RODS), and the Medical Research Council Sum Score (MRCSS).  Results: Significant associations were determined between initial deficit and ONLS score (P =.002) and MRCSS improvement (P =.001) but not I-RODS score. A strong inverse correlation was observed between disease duration and I-RODS score(P =.002) but not ONLS/MRCSS improvement. A strong association was observed between age ≤ 40 years and I-RODS score (P =.001) but not ONLS/MRCSS improvement. When minimum important differences were used, ONLS and I-RODS sensitivities were comparable (P =.19).  Discussion: Overall Neuropathy Limitation Scale and I-RODS are equally sensitive in identifying change. Ease of administration, better ability to detect improvement in severe disease, and greater amplitude responses throughout the disease and in older patients favor the ONLS. The I-RODS appears more useful in early disease/younger patients.