Assessing deterioration using impairment and functional outcome measures in chronic inflammatory demyelinating polyneuropathy: A post‐hoc analysis of the immunoglobulin overtreatment in CIDP trial

Abstract

It is unclear whether frequently used cutoff values for outcome measures defining minimal clinically important differences (MCIDs) can accurately identify meaningful deterioration in chronic inflammatory demyelinating polyneuropathy (CIDP). We used data from the immunoglobulin overtreatment in CIDP (IOC) trial, in which 60 clinically stable patients with CIDP were randomized to intravenous immunoglobulin (IVIg) withdrawal or continuation. We calculated change scores of the Inflammatory Rasch-Built Overall Disability Scale (I-RODS), grip strength, and Medical Research Council-sum score (MRC-SS) and classified visits based on a treatment anchor (ie, decision to restart/ increase treatment after reaching a predefined early endpoint of deterioration). The variability of scores in patients without deterioration was calculated using the limits of agreement. We defined optimized MCIDs for deterioration and specific combinations of MCIDs from different outcome measures, and subsequently calculated the accuracies of the (combined) MCIDs. Substantial variability was found in scores of the I-RODS, grip strength and MRC-SS in patients without deterioration over time, and most MCIDs were within the limits of the variability observed in patients without deterioration. Some MCID cut-offs were insensitive but highly specific for detecting deterioration, for example, the MCID-SE of À1.96 of the I-RODS and À2 point on the MRC-SS.Others were sensitive, but less specific, for example, À4 centiles of the I-RODS. Some combined MCIDs resulted in high specificities and moderate sensitivities. Our results suggest that clinically important deterioration cannot be distinguished from variability over time with currently used MCIDs on the individual level. Combinations of MCIDs might improve the accuracy of determining deterioration, but this needs validation.

Challenges in the Early Diagnosis and Treatment of Chronic Inflammatory Demyelinating Polyradiculoneuropathy in Adults: Current Perspectives

“…However, using the current MCIDs, it can be challenging to differentiate genuine clinical deterioration from variability over time at an individual level. 93 The revised EAN/PNS 2021 guideline strongly recommends the use of at least one impairment and one disability scale to determine deterioration. While combining multiple MCIDs might enhance the accuracy, it has yet to be validated.…”

“… 12 The use of minimal clinically important differences (MCIDs) to define meaningful improvement or deterioration can be useful, but do not rule out normal daily or irrelevant fluctations. 93 Optimal timing for evaluating treatment and dosing can be found in Table 4 . Based on the selected treatment modality, a therapeutic response often manifests after several weeks or months.…”

Safety and Efficacy of Pulmonary Rehabilitation for Long COVID Patients Experiencing Long-Lasting Symptoms

“…This indicator is adapted for individual analysis and can be used to determine deterioration [49]. By contrast, classical MCIDs, which are developed to perceive a beneficial change only, can be smaller or larger when assessing a deterioration and are, therefore, not suitable for that purpose [50][51][52][53][54].…”