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

Treatment response amplitude and timing in chronic inflammatory demyelinating polyneuropathy with routine care: Study of a UK cohort

BACKGROUND AND PURPOSE

The amplitude, timing, and determinants of improvement with available treatments are uncertain in chronic inflammatory demyelinating polyneuropathy (CIDP). Our primary objective was to quantify categorized outcomes with routine care.

METHODS

We retrospectively studied treatment response within 36 months from initiation in 112 consecutive subjects with CIDP. Response was classified into a proposed new "CIDP treatment-response category" (CT-RC), based on achieved endpoints. Determinants of the CT-RC, of timing of maximum improvement, and of treatment discontinuation were ascertained.

RESULTS

The CT-RC demonstrated high concurrent validity with current outcome measures. Thirty-six subjects (32.1%) achieved a "complete response," 37 (33%) a "good partial response," 10 (8.9%) a "moderate partial response," and 15 (13.4%) a "poor partial response." Fourteen subjects (12.5%) were "nonresponsive." The CT-RC was independently predicted only by age. Mean time to maximum improvement was 12.1 months (range = 1-36) and was not associated with any pretreatment covariate. Treatment discontinuation occurred in 24 of 62 (38.2%) partial responders and was only associated with shorter pretreatment disease duration. Nonresponders were older and received a similar number of treatments compared to responders.

CONCLUSIONS

CT-RC classification indicates persistent disability in >60% of treatment responders in CIDP. Timing of maximum improvement is variable, frequently delayed, and unpredictable. Treatment withdrawal without deterioration is achievable in approximately 40% of subjects and may be more likely with prompt treatment. Treatment withdrawal in partial responders and limited escalation in nonresponders suggest implication of physician- and patient-related factors in suboptimal response. More effective treatments/treatment methods and better understanding of other factors influencing response are needed in CIDP.

Chronic Inflammatory Demyelinating Polyradiculoneuropathy: Current Therapeutic Approaches and Future Outlooks

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a treatable autoimmune disorder, for which different treatment options are available. Current first-line evidence-based therapies for CIDP include intravenous and subcutaneous immunoglobulins, corticosteroids and plasma exchanges. Despite lack of evidence, cyclophosphamide, rituximab and mycophenolate mofetil are commonly used in circumstances of refractoriness and, more debatably, of perceived overdependence on first-line therapies. Rituximab is currently the object of a randomized controlled trial for CIDP. Based on case series, and although rarely considered, haematopoietic autologous stem cell transplants may be effective in refractory disease, with low mortality and high remission rates. A new therapeutic option has appeared with efgartigimod, a neonatal Fc receptor blocker, recently shown to significantly lower relapse rate versus placebo, after withdrawal from previous immunotherapy. Other neonatal Fc receptor blockers, nipocalimab and batoclimab, are under study. The C1 complement-inhibitor SAR445088, acting in the proximal portion of the classical complement system, is currently the subject of a new study in treatment-responsive, refractory and treatment-naïve subjects. Finally, Bruton Tyrosine Kinase inhibitors, which exert anti-B cell effects, may represent another future research avenue. The widening of the therapeutic armamentarium enhances the need for improved evaluation of treatment effects and reliable biomarkers in CIDP.

Impact of social-functioning and sleep on quality of life in chronic inflammatory demyelinating polyneuropathy

INTRODUCTION/AIMS

The impact of impairment of social functioning and sleep on health-related quality of life (HR-QoL), is unknown in chronic inflammatory demyelinating polyneuropathy (CIDP). The value of the Chronic Acquired Polyneuropathy Patient-Reported Index (CAP-PRI) to identify potential social functioning and sleep issues is equally unknown.

METHODS

We performed a cross-sectional evaluation of social functioning and sleep using the "Scales for Outcomes in Parkinson's Disease" (SCOPA) in 40 subjects with clinically-stable CIDP through a structured questionnaire. We assessed HR-QoL through the CAP-PRI. Disability was evaluated through the Overall Neuropathy Limitation Score (ONLS).

RESULTS

SCOPA social functioning scores were impaired at least "a little" per averaged item in > 50 % of subjects, and at least "quite a bit" per averaged item in > 20 %. Most affected items were (i) difficulty with work/household/other chores (ii) difficulties with hobbies/sport/leisure activities. SCOPA sleep sub-scores indicated at least "a little concern" for night-time sleep in nearly 50 % of subjects. Abnormal sleep timing was rare. Associations were found between both SCOPA social-functioning and SCOPA sleep scores and the CAP-PRI. Linear regression demonstrated the SCOPA social-functioning score was independently associated with the CAP-PRI. The CAP-PRI showed high association with disability scores, good internal consistency, absence of ceiling effect, absence of significant floor-effect, and good criteria-related as well as construct-related validity.

DISCUSSION

Social functioning and night-time sleep are frequently affected in CIDP and impact on HR-QoL. In contrast to traditional disability scales, the CAP-PRI additionally allows adequately capturing these impairments and may represent an adequate holistic outcome measure.

Current clinical management of CIDP with immunoglobulins in France: An expert opinion

Treatment strategies in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) must be adapted on a case-to-case basis. Validated and reproducible tools for monitoring treatment response are required at diagnosis, when initiating treatment and throughout follow-up. A task force of French neurologists, experts in neuromuscular disease reference centers, was assembled to provide expert advice on the management of typical CIDP with intravenous immunoglobulins (Ig), and to harmonize treatment practices in public and private hospitals. The task force also referred to the practical experience of treating CIDP with Ig at the diagnostic, induction and follow-up stages, including the assessment and management of Ig dependence, and following the recommendations of the French health agency.

Effectiveness and safety of rituximab in autoimmune nodopathy: a single-center cohort study

Autoimmune nodopathy is a peripheral neuropathy characterized by acquired motor and sensory deficit with autoantibodies against the node of Ranvier or paranodal region in the peripheral nervous system. The clinical and pathological characteristics of the disease are distinct from that of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), and the standard treatment for CIDP is partially effective. Rituximab is a chimeric monoclonal antibody which binds and depletes B cells in peripheral blood. This prospective observational study included 19 patients with autoimmune nodopathy. Participants received intravenous rituximab treatment 100 mg the first day and 500 mg the next day and given every 6 months. The Inflammatory Neuropathy Cause and Treatment (INCAT) disability score, Inflammatory Rasch-Built Overall Disability Scale (I-RODS), Medical Research Council (MRC) sum score, and Neuropathy Impairment Score (NIS) were collected at entry and before the rituximab infusion every 6 months. At the last visit, 94.7% (18/19) of the patients showed clinical improvement on either the INCAT, I-RODS, MRC, or NIS scale. After the first infusion, 9 patients (47.7%) showed improvement on the INCAT score, and 11 patients (57.9%) on cI-RODS. In patients who received more than one rituximab infusion, the improvement of INCAT score and cI-RODS at the last assessment was higher than that after the first infusion. We also observed tapered or withdrawn concomitant oral medications in these patients.

Application of the 2021 EAN/PNS criteria for chronic inflammatory demyelinating polyneuropathy

BACKGROUND

The diagnostic value of new criteria of the European Academy of Neurology/Peripheral Nerve Society (EAN/PNS) for chronic inflammatory demyelinating polyneuropathy (CIDP) is unknown.

METHODS

We performed a retrospective study of fulfilment of EAN/PNS 2021 criteria on 120 consecutive patients with a clinical diagnosis of 'suspected CIDP' and objective treatment response, attending University Hospitals Birmingham, UK. Specificity was evaluated versus 100 consecutive controls.

RESULTS

The sensitivity of EAN/PNS criteria for 'CIDP' was 83.3%. The sensitivity for 'CIDP' or 'possible CIDP' was 93.3%. Specificity was of 94% for 'CIDP' and 79% for 'CIDP' or 'possible CIDP'. No sensitivity/specificity differences were ascertained with previous versions ('CIDP': sensitivity: 83.3% vs 81.3%, p=0.74, specificity: 94% vs 96.1%, p=0.38, respectively; 'CIDP' or 'possible CIDP': sensitivity: 93.3% vs 96.7%, p=0.25 and specificity: 79% vs 69.2 %, p=0.09, respectively). F-wave prolongation, proximal and distal temporal dispersion were the most likely parameters to contribute to false positives, whereas distal motor latency was the least likely. No impact of sensory electrophysiology could be ascertained. 'Typical CIDP' represented 79% of the CIDP cohort. The largest component of the 'variant CIDP' group was represented by focal/multifocal forms (14%). With new criteria, 6.7% of the cohort did not meet requirements, among whom the majority (75%) had paranodopathy or chronic immune sensory polyradiculopathy (CISP).

DISCUSSION

The sensitivity and specificity of new EAN/PNS criteria for CIDP is equivalent to that of previous versions. The exclusion of paranodopathies and CISP from the CIDP spectrum impacts on management of a non-negligible proportion of treatment-responsive patients.

Usefulness and prognostic value of diagnostic tests in patients with possible chronic inflammatory demyelinating polyradiculoneuropathy

INTRODUCTION/AIMS

Recent guidelines define chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and possible CIDP. The aims of our study were to evaluate the value of diagnostic tests to support the diagnosis of CIDP in patients with possible CIDP and to identify prognostic factors of therapeutic success.

METHODS

We conducted an observational retrospective two-center study between 2014 and 2019. We selected patients with a clinical presentation suggesting CIDP, but whose electrodiagnostic (EDX) test results did not meet the EFNS/PNS 2021 criteria. We analyzed epidemiologic and clinical features, axonal loss on EDX, cerebrospinal fluid (CSF), somatosensory evoked potentials (SSEPs), plexus magnetic resonance imaging (MRI), nerve biopsy, and therapeutic response.

RESULTS

We selected 75 patients, among whom 30 (40%) responded to treatment. The positivity rates of CSF analysis, MRI and SSEPs were not influenced by the clinical presentation or by the delay between symptom onset and medical assessment. A high protein level in CSF, female gender, and a relapsing-remitting course predicted the therapeutic response.

DISCUSSION

It is important to properly diagnose suspected CIDP not meeting EFNS/PNS 2021 EDX criteria by using supportive criteria. Specific epidemiological factors and a raised CSF protein level predict a response to treatment. Further prospective studies are needed to improve diagnosis and the prognostic value of diagnostic tests in CIDP.

Assessing deterioration using impairment and functional outcome measures in chronic inflammatory demyelinating polyneuropathy: a post-hoc analysis of the IOC trial

BACKGROUND AND AIMS

It is unclear whether frequently used cut-off values for outcome measures defining minimal clinically important differences (MCIDs) can accurately identify meaningful deterioration in chronic inflammatory demyelinating polyneuropathy (CIDP).

METHODS

We used data from the IOC trial, in which sixty clinically stable CIDP patients were randomized to IVIg withdrawal or continuation. We calculated change scores of the Inflammatory Rasch-Built Overall Disability Scale (I-RODS), grip strength, and MRC sum score (MRC-SS) and classified visits based on a treatment anchor (i.e. 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.

RESULTS

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, e.g. the MCID-SE of -1.96 of the I-RODS and -2 point on the MRC-SS. Others were sensitive, but less specific, e.g. -4 centiles of the I-RODS. Some combined MCIDs resulted in high specificities and moderate sensitivities.

INTERPRETATION

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.

Contemporary challenges in the diagnosis and management of chronic inflammatory demyelinating polyneuropathy

INTRODUCTION

Despite extensive research, multiple inter-related diagnostic and management challenges remain for chronic inflammatory demyelinating polyneuropathy (CIDP).

AREAS COVERED

A literature review was performed on diagnosis and treatment in CIDP. The clinical features and disease course were evaluated. Investigative techniques, including electrophysiology, cerebrospinal fluid examination, neuropathology, imaging and neuroimmunology, were considered in relation to technical aspects, sensitivity, specificity, availability and cost. Available evidenced-based treatments and those with possible efficacy despite lack of evidence, were considered, as well as current methods for evaluation of treatment effects.

EXPERT OPINION

CIDP remains a clinical diagnosis, supported first and foremost by electrophysiology. Other investigative techniques have limited impact. Most patients with CIDP respond to available first-line treatments and immunosuppression may be efficacious in those who do not. Consideration of the natural history and of the high reported remission rate, of under-recognised associated disabling features, of treatment administration modalities and assessment methods, require enhanced attention.

Evidence base for investigative and therapeutic modalities in chronic inflammatory demyelinating polyneuropathy and multifocal motor neuropathy

Chronic inflammatory demyelinating polyneuropathy, its variants and multifocal motor neuropathy belong to a spectrum of peripheral nerve disorders with complex dysimmune disease mechanisms. Awareness of the unique clinical phenotypes but also heterogeneity between patients is vital to arrive at early suspicion and ordering appropriate tests. This includes requirements for optimal electrodiagnostic protocol, aimed to capture sufficient electrophysiologic evidence for relevant abnormalities, a case-based approach on the eventual need to further expand the diagnostic armamentarium and correct reading of their results. Considerable phenotypical variation, diverse combinations of abnormalities found on diagnostic tests and heterogeneity in disease course and treatment response, all contribute to widespread differences in success rates on timely diagnosis and optimal treatment. We aim to provide a practical overview and guidance on relevant diagnostic and management strategies, including pitfalls and present a summary of the relevant novel developments in this field.

Predicting long-term trends in inflammatory neuropathy outcome measures using latent class modelling

BACKGROUND

Immunoglobulin (Ig) is used to treat chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and multifocal motor neuropathy with conduction block (MMNCB). Regular infusions may be used for symptom control. Disease activity is monitored with clinical outcome measurements. We examined outcome measure variation during clinically stable periods in Ig-treated CIDP and MMNCB patients. We explored utility of serial outcome measurement in long-term outcome prediction.

METHODS

Retrospective longitudinal analysis of a single neuroscience centre's Ig-treated CIDP and MMNCB patients, 2009-2020, was performed. Mean and percentage change for grip strength, Rasch-built overall disability scales (RODS) and MRC sum scores (MRC-SS) during periods of clinical stability were compared to score-specific minimal clinically important differences (MCID). Latent class mixed modelling (LCMM) was used to identify longitudinal trends and factors influencing long-term outcome.

RESULTS

We identified 85 CIDP and 23 MMNCB patients (1,423 datapoints; 5635 treatment-months). Group-averaged outcome measures varied little over time. Intra-individual variation exceeded MCID for RODS in 44.2% CIDP and 16.7% MMNCB datapoints, grip strength in 10.6% (CIDP) and 8.8%/27.2% (MMNCB right/left hand) and MRC-SS in 43.5% (CIDP) and 20% (MMNCB). Multivariate LCMM identified subclinical trends toward improvement (32 patients) and deterioration (73 patients) in both cohorts. At baseline, CIDP 'deteriorators' were older than 'improvers' (66.2 versus 57 years, p=0.025). No other individual factors predicted categorisation. The best model for 'deteriorator' identification was contiguous sub-MCID decline in more than one outcome measure (CIDP: sensitivity 74%, specificity 59%; MMNCB: sensitivity 73%, specificity 88%).

DISCUSSION

Outcome measure interpretation determines therapeutic decision-making in Ig-dependent neuropathy patients, but intra-individual variation is common, often exceeding MCID. Here we show sub-MCID contiguous changes in more than one outcome measurement are a better predictor of long-term outcome. This article is protected by copyright. All rights reserved.

Antecedent infections and vaccinations in chronic inflammatory demyelinating polyneuropathy: A European collaborative study

INTRODUCTION/AIMS

Chronic inflammatory demyelinating polyneuropathy (CIDP) may be rarely preceded by infection. A causative link remains unproven, in contrast to Guillain-Barré syndrome (GBS), which is commonly postinfectious with well-demonstrated pathophysiological mechanisms of molecular mimicry following Campylobacter jejuni enteritis. Uncommonly, infections are reported before the onset of CIDP. In this study we aimed to determine the frequency and characteristics of CIDP occurring after antecedent infections or vaccinations in two large European cohorts.

METHODS

We reviewed the records of 268 subjects with "definite" or "probable" CIDP from the Inflammatory Neuropathy Clinic, Birmingham, UK (129 subjects), and from the Serbian national CIDP database (139 subjects).

RESULTS

Twenty-five of 268 (9.3%) subjects had a respiratory or gastrointestinal infection in the 6 weeks preceding CIDP onset, and 3 of 268 (1.1%) had received an influenza vaccination. CIDP disease onset occurred at a younger age (mean [standard deviation], 44.25 [17.36] years vs 54.05 [15.19] years; P < .005) and acute-onset CIDP was more common (42.9% vs 12.1%; odds ratio, 5.46; 95% confidence interval, 2.35-12.68; P < .001) in subjects with preceding infections or vaccinations. No differences in CIDP subtype, rates of cerebrospinal fluid protein level elevation, disability, or likelihood of treatment response, were observed.

DISCUSSION

Antecedent infections or vaccinations may precede about 10% of cases of CIDP and are more common in younger subjects. Acute-onset CIDP is more frequent after antecedent events. These findings may suggest specific pathophysiological mechanisms in such cases.