Correlation of the patient's reported outcome Inflammatory-RODS with an objective metric in immune-mediated neuropathies

Background and purpose: There is increasing interest in using patient-reported outcome measures (PROMs) in clinical studies to capture individual changes over time. However, PROMs have also been criticized because they are entirely subjective. Our objective was to examine the relationship between a subjective PROM and an objective outcome tool in patients with Guillain–Barré syndrome (GBS), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and gammopathy-related polyneuropathy (MGUSP). Methods: The Inflammatory Rasch-built Overall Disability Scale (I-RODS©, a multi-item scale that examines functionality) was completed by 137 patients with newly diagnosed (or relapsing) GBS (55), CIDP (59) and MGUSP (23) who were serially examined (GBS/CIDP, T0/T1/T3/T6/T12 months; MGUSP, T0/T3/T12). Possible association between the I-RODS findings and the vigorimeter scores, an objective linear instrument to assess grip strength, was examined. Results: A significant correlating trend was found between the I-RODS and grip strength scores for the overall group and in each illness, independently. Conclusion: The objectivity of patients' subjective report on their functional state based on a strong correlation between the I-RODS and grip strength in patients with GBS, CIDP and MGUSP has been demonstrated. These findings provide further support to use the I-RODS and grip strength in future clinical studies in these conditions.