Withdrawal of intravenous immunoglobulin in chronic inflammatory demyelinating polyradiculoneuropathy

Efficacy, safety and tolerability of rozanolixizumab in patients with chronic inflammatory demyelinating polyradiculoneuropathy: a randomised, subject-blind, investigator-blind, placebo-controlled, phase 2a trial and open-label extension study

BACKGROUND

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a peripheral nerve disorder characterised by weakness and sensory loss. We assessed the neonatal Fc receptor inhibitor rozanolixizumab for CIDP management.

METHODS

CIDP01 (NCT03861481) was a randomised, subject-blind, investigator-blind, placebo-controlled, phase 2a study. Adults with definite or probable CIDP receiving subcutaneous or intravenous immunoglobulin maintenance therapy were randomised 1:1 to 12 once-weekly subcutaneous infusions of rozanolixizumab 10 mg/kg or placebo, stratified according to previous immunoglobulin administration route. Investigators administering treatment and assessing efficacy, and patients, were blinded. The primary outcome was a change from baseline (CFB) to day 85 in inflammatory Rasch-built Overall Disability Scale (iRODS) score. Eligible patients who completed CIDP01 entered the open-label extension CIDP04 (NCT04051944).

RESULTS

In CIDP01, between 26 March 2019 and 31 March 2021, 34 patients were randomised to rozanolixizumab or placebo (17 (50%) each). No significant difference in CFB to day 85 in iRODS centile score was observed between rozanolixizumab (least squares mean 2.0 (SE 3.2)) and placebo (3.4 (2.6); difference -1.5 (90% CI -7.5 to 4.5)). Overall, 14 (82%) patients receiving rozanolixizumab and 13 (76%) receiving placebo experienced a treatment-emergent adverse event during the treatment period. Across CIDP01 and CIDP04, rozanolixizumab was well tolerated over up to 614 days; no clinically meaningful efficacy results were seen. No deaths occurred.

CONCLUSIONS

Rozanolixizumab did not show efficacy in patients with CIDP in this study, although this could be due to a relatively high placebo stability rate. Rozanolixizumab was well tolerated over medium-to-long-term weekly use, with an acceptable safety profile.

Immunoglobulin use in neurology: a practical approach

Human immunoglobulin, delivered either intravenously (IVIg) or subcutaneously, is used to treat a range of immune-mediated neurological disorders. It has a role in acute or subacute inflammatory disease control and as a maintenance therapy in chronic disease management. This review considers mechanisms of IVIg action and the evidence for IVIg in neurological conditions. We use Guillain-Barré syndrome and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) as frameworks to demonstrate an approach to IVIg use in acute and chronic dysimmune neurological conditions across two different healthcare systems: the UK and Australia. We highlight the benefits and limitations of IVIg and focus on practical considerations such as informed consent, managing risks and adverse effects, optimal dosing and monitoring response. We use these basic clinical practice principles to discuss the judicious use of an expensive and scarce blood product with international relevance.

Proximity extension assay-based discovery of biomarkers for disease activity in chronic inflammatory demyelinating polyneuropathy

BACKGROUND

Objective disease activity biomarkers are lacking in chronic inflammatory demyelinating polyneuropathy (CIDP), impacting treatment decisions in clinical care and outcomes in clinical trials. Using a proximity extension assay, we aimed to identify candidate serum protein biomarkers for disease activity in CIDP.

METHOD

We collected clinical data and serum of 106 patients with CIDP. Patients starting induction treatment (n=53) and patients on maintenance treatment starting treatment withdrawal (n=40) were assessed at baseline and at 6 months (or at relapse). Patients in remission (n=13) were assessed once. Clinical disease activity was defined based on improvement or deterioration by the minimal clinically important difference on the inflammatory Rasch-built Overall Disability Scale in combination with either grip strength or the Medical Research Council sum score. Using a proximity extension assay (Olink Explore platform), 1472 protein levels were analysed in serum. Candidate proteins were selected based on fold change>0.5 or <-0.5 and p<0.05 between clinically active and inactive disease. Longitudinal changes of candidate proteins between baseline and follow-up were analysed.

RESULTS

We identified 48 candidate proteins that differed between clinically active and inactive disease on cross-sectional comparison. Five of these proteins (SUGT1, IRAK4, DCTN1, 5'-nucleotidase cytosolic IIIA (NT5C3A), glutaredoxin (GLRX)) also showed longitudinal changes consistent with disease activity changes. IRAK4 was also identified in a sensitivity analysis, using another definition for disease activity.

CONCLUSION

Our results indicate that IRAK4 and possibly SUGT1, DCTN1, NT5C3A and GLRX are candidate biomarkers for monitoring clinical disease activity in CIDP.

[Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)]

Chronic inflammatory demyelinating polyneuropathy (CIDP) is the most common chronic autoimmune disease of the peripheral nervous system. It is often difficult to diagnose, but severaly therapeutic options are nowadays available to reduce neurological deficits and to improve the disease course. This article exemplifies the management of CIDP by a typical case study.

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.

Clinical relevance of distinguishing autoimmune nodopathies from CIDP: longitudinal assessment in a large cohort

BACKGROUND

The aim of this study was to determine treatment response and whether it is associated with antibody titre change in patients with autoimmune nodopathy (AN) previously diagnosed as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), and to compare clinical features and treatment response between AN and CIDP.

METHODS

Serum IgG antibodies to neurofascin-155 (NF155), contactin-1 (CNTN1) and contactin-associated protein 1 (CASPR1) were detected with cell-based assays in patients diagnosed with CIDP. Clinical improvement was determined using the modified Rankin scale, need for alternative and/or additional treatments and assessment of the treating neurologist.

RESULTS

We studied 401 patients diagnosed with CIDP and identified 21 patients with AN (10 anti-NF155, 6 anti-CNTN1, 4 anti-CASPR1 and 1 anti-NF155/anti-CASPR1 double positive). In patients with AN ataxia (68% vs 28%, p=0.001), cranial nerve involvement (34% vs 11%, p=0.012) and autonomic symptoms (47% vs 22%, p=0.025) were more frequently reported; patients with AN improved less often after intravenous immunoglobulin treatment (39% vs 80%, p=0.002) and required additional/alternative treatments more frequently (84% vs 34%, p<0.001), compared with patients with CIDP. Antibody titres decreased or became negative in patients improving on treatment. Treatment withdrawal was associated with a titre increase and clinical deterioration in four patients.

CONCLUSIONS

Distinguishing CIDP from AN is important, as patients with AN need a different treatment approach. Improvement and relapses were associated with changes in antibody titres, supporting the pathogenicity of these antibodies.

Updated consensus statement: Intravenous immunoglobulin in the treatment of neuromuscular disorders report of the AANEM ad hoc committee

Intravenous immune globulin (IVIG) is an immune-modulating biologic therapy that is increasingly being used in neuromuscular disorders despite the paucity of high-quality evidence for various specific diseases. To address this, the AANEM created the 2009 consensus statement to provide guidance on the use of IVIG in neuromuscular disorders. Since then, there have been several randomized controlled trials for IVIG, a new FDA-approved indication for dermatomyositis and a revised classification system for myositis, prompting the AANEM to convene an ad hoc panel to update the existing guidelines.New recommendations based on an updated systemic review of the literature were categorized as Class I-IV. Based on Class I evidence, IVIG is recommended in the treatment of chronic inflammatory demyelinating polyneuropathy, Guillain-Barré Syndrome (GBS) in adults, multifocal motor neuropathy, dermatomyositis, stiff-person syndrome and myasthenia gravis exacerbations but not stable disease. Based on Class II evidence, IVIG is also recommended for Lambert-Eaton myasthenic syndrome and pediatric GBS. In contrast, based on Class I evidence, IVIG is not recommended for inclusion body myositis, post-polio syndrome, IgM paraproteinemic neuropathy and small fiber neuropathy that is idiopathic or associated with tri-sulfated heparin disaccharide or fibroblast growth factor receptor-3 autoantibodies. Although only Class IV evidence exists for IVIG use in necrotizing autoimmune myopathy, it should be considered for anti-hydroxy-3-methyl-glutaryl-coenzyme A reductase myositis given the risk of long-term disability. Insufficient evidence exists for the use of IVIG in Miller-Fisher syndrome, IgG and IgA paraproteinemic neuropathy, autonomic neuropathy, chronic autoimmune neuropathy, polymyositis, idiopathic brachial plexopathy and diabetic lumbosacral radiculoplexopathy.

Serum B-cell activating factor is not a potential biomarker for disease activity in chronic inflammatory demyelinating polyneuropathy

B-cell activating factor (BAFF) is a crucial cytokine for differentiation and survival of B-cells and correlates to disease activity in some auto-immune diseases. To evaluate BAFF as a biomarker for disease activity in chronic inflammatory demyelinating polyneuropathy (CIDP), serum BAFF levels were measured at varying disease stages: patients starting treatment, patients starting treatment withdrawal, patients in remission and healthy controls. Serum BAFF levels were elevated in patients compared to healthy controls, but did not differ between patients starting treatment and patients in remission. Serum BAFF levels did not change with or predict treatment response or relapse. Serum BAFF is not a responsive biomarker reflecting disease activity in CIDP.

Introducing electronic monitoring of disease activity in patients with chronic inflammatory demyelinating polyneuropathy (EMDA CIDP): trial protocol of a proof of concept study

INTRODUCTION

Chronic inflammatory demyelinating polyneuropathy (CIDP) is one of the most common immune neuropathies leading to severe impairments in daily life. Current treatment options include intravenous immunoglobulins (IVIG), which are administered at intervals of 4-12 weeks. Determination of individual treatment intervals is challenging since existing clinical scores lack sensitivity to objectify small, partially fluctuating deficits in patients. End-of-dose phenomena described by patients, manifested by increased fatigue and worsening of (motor) symptoms, are currently difficult to detect. From a medical and socio-economic point of view, it is necessary to identify and validate new, more sensitive outcome measures for accurate mapping of disease progression and, thus, for interval finding. Digital health technologies such as wearables may be particularly useful for this purpose, as they record real-life data and consequently, in contrast to classic clinical 'snapshots', can continuously depict the disease course.

METHODS

In this prospective, observational, non-interventional, single-center, investigator-initiated study, CIDP patients treated with IVIG will be continuously monitored over a period of 6 months. Clinical scores and blood analyses will be assessed and collected during three visits (V1, V2, V3). Additionally, activity, sleep, and cardiac parameters will be recorded over the entire period using a wearable device. Further, patients' subjective disease development and quality of life will be recorded at various visits (read-outs). The usability of the smartwatch will be assessed at the end of the study.

PERSPECTIVE

The study aims to evaluate different digital measurements obtained with the smartwatch and blood-based analyses for monitoring disease activity and progress in CIDP patients. In conjunction, both means of monitoring might offer detailed insights into behavioral and biological patterns associated with treatment-related fluctuations such as end-of-dose phenomena.

TRIAL REGISTRATION

The study protocol was registered at ClinicalTrials.gov. Identifier: NCT05723848. Initially, the protocol was submitted prospectively on January 10, 2023. The trial was publicly released after formal improvements on February 13, 2023, after first patients were included according to the original protocol.

Immunotherapy responsiveness and risk of relapse in Down syndrome regression disorder

Down syndrome regression disorder (DSRD) is a clinical symptom cluster consisting of neuropsychiatric regression without an identifiable cause. This study evaluated the clinical effectiveness of IVIg and evaluated clinical characteristics associated with relapse after therapy discontinuation. A prospective, multi-center, non-randomized, observational study was performed. Patients met criteria for DSRD and were treated with IVIg. All patients underwent a standardized wean-off therapy after 9-12 months of treatment. Baseline, on-therapy, and relapse scores of the Neuropsychiatric Inventory Total Score (NPITS), Clinical Global Impression-Severity (CGI-S), and the Bush-Francis Catatonia Rating Scale (BFCRS) were used to track clinical symptoms. Eighty-two individuals were enrolled in this study. Patients had lower BFCRS (MD: -6.68; 95% CI: -8.23, -5.14), CGI-S (MD: -1.27; 95% CI: -1.73, -0.81), and NPITS scores (MD: -6.50; 95% CI: -7.53, -5.47) while they were on therapy compared to baseline. Approximately 46% of the patients (n = 38) experienced neurologic relapse with wean of IVIg. Patients with neurologic relapse were more likely to have any abnormal neurodiagnostic study (χ2 = 11.82, P = 0.001), abnormal MRI (χ2 = 7.78, P = 0.005), and abnormal LP (χ2 = 5.45, P = 0.02), and a personal history of autoimmunity (OR: 6.11, P < 0.001) compared to patients without relapse. IVIg was highly effective in the treatment of DSRD. Individuals with a history of personal autoimmunity or neurodiagnostic abnormalities were more likely to relapse following weaning of immunotherapy, indicating the potential for, a chronic autoimmune etiology in some cases of DSRD.

Parameters Associated with the Required Drug Dose of Intravenous Immunoglobulin in Stable Chronic Inflammatory Demyelinating Polyradiculoneuropathy

Background: Intravenous immunoglobulin (IVIg) is efficient and one of very few treatment options for patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). However, finding the optimal dose of IVIg for individual CIDP patients remains challenging. The dose of IVIg needs to be adjusted individually. Considering the high healthcare costs of IVIg therapy, the overtreatment of some patients seen in placebo studies and the shortage of IVIg we recently experienced, as well as identifying factors associated with the required dose of IVIg in maintenance treatment, is extremely important. Thus, in this retrospective study, we analyze characteristics of patients with stable CIDP, which are associated with the required drug dose. Methods: 32 patients with stable CIDP treated with IVIg between July 2021 and July 2022 were identified from our database and included in this retrospective study. Patients’ characteristics were registered, and parameters were identified that were associated with the IVIg dose. Results: Age, cerebrospinal fluid protein elevation, disease duration, delay between symptom onset/diagnosis, Inflammatory Neuropathy Cause and Treatment (INCAT) score, and Medical Research Council Sum Score (MRC SS) were significantly associated with the required drug dose. In addition, an association of age, sex, elevated CSF protein, time interval between symptom onset and diagnosis, and the MRC SS with the required IVIg dose could be demonstrated in the multivariable regression analysis. Conclusions: Our model, which is based on routine parameters that are simple to address in the clinical practice, can be useful in adjusting the IVIg dose in patients with stable CIDP.

Immunotherapy Responsiveness and Risk of Relapse in Down Syndrome Regression Disorder

Down syndrome regression disorder (DSRD) is a clinical symptom cluster consisting of neuropsychiatric regression without an identifiable cause. This study evaluated the clinical effectiveness of IVIg and evaluated clinical characteristics associated with relapse after therapy discontinuation. A prospective, multi-center, non-randomized, observational study was performed. Patients met criteria for DSRD and were treated with IVIg. All patients underwent a standardized wean off therapy after 9-12 months of treatment. Baseline, on therapy, and relapse scores of the Neuropsychiatric Inventory Total Score (NPITS), Clinical Global Impression-Severity (CGI-S), and the Bush-Francis Catatonia Rating Scale (BFCRS) were used to track clinical symptoms. Eighty-two individuals were enrolled in this study. Patients had lower BFCRS (MD: -6.68; 95% CI: -8.23, -5.14), CGI-S (MD: -1.27; 95% CI: -1.73, -0.81), and NPITS scores (MD: -6.50; 95% CI: -7.53, -5.47) while they were on therapy compared to baseline. Approximately 46% of the patients (n = 38) experienced neurologic relapse with wean of IVIg. Patients with neurologic relapse were more likely to have any abnormal neurodiagnostic study (χ2 = 11.82, p = 0.001), abnormal MRI (χ2 = 7.78, p = 0.005), and abnormal LP (χ2 = 5.45, p = 0.02), and a personal history of autoimmunity (OR: 6.11, p < 0.001) compared to patients without relapse. IVIg was highly effective in the treatment of DSRD. Individuals with a history of personal autoimmunity or neurodiagnostic abnormalities were more likely to relapse following weaning of immunotherapy, indicating the potential for, a chronic autoimmune etiology in some cases of DSRD.

IvIG bei CIDP: Ein Absetzversuch ist möglich

Intravenöse Immunoglobuline (IVIg) stellen eine wirksame Therapie der chronischen inflammatorischen demyelinisierenden Polyradikuloneuropathie (CIDP) dar. Der Verlauf der Erkrankung ist unterschiedlich, Biomarker für die Krankheitsaktivität fehlen. Das erschwert die Entscheidung für ein Absetzen der IVIg. Die Fortführung der Therapie kann bei stabiler Erkrankung auf der anderen Seite eine Übertherapie bedeuten und hohe Kosten verursachen.

Standardized Tapering off Subcutaneous Immunoglobulin in Chronic Inflammatory Demyelinating Polyneuropathy

BACKGROUND

Attempting discontinuation of treatment in patients with chronic inflammatory demyelinating polyneuropathy (CIDP) is recommended. However, there is no evidence based regimen for tapering off subcutaneous immunoglobulin (SCIG). This trial investigated stepwise tapering off SCIG to detect remission and the lowest effective dosage. During tapering off, frequent vs less frequent clinical evaluation was compared.

METHODS

Patients with CIDP receiving a stable SCIG dosage followed a standardized tapering off regimen: 90%, 75%, 50%, 25% and 0% of the initial dose every 12th week, pending no deterioration occurred. In case of relapse during tapering off, the lowest effective dose was identified. Treatment with SCIG was registered for two years after participation. Disability score and grip strength were primary parameters. Participants were randomized to clinical evaluation every 6th week (frequent) or 12th week (less frequent).

RESULTS

Fifty-five patients were included of which thirty-five relapsed. Twenty patients (36%) were able to discontinue treatment without relapse. In relapsing patients, median dosage could be reduced by 10% (range, 0-75). After two years, 18 of 20 patients were still in remission without treatment. Frequent clinical evaluation did not detect deterioration more frequently than less frequent evaluation; RR 0.5 (95% CI, 0.2-1.2) (p = 0.17).

CONCLUSION

In stable CIDP patients, SCIG could be completely tapered off in 36% of the patients and only in 10% of these patients relapse occurred during the following two years. More frequent evaluation was not superior to detect deterioration.

What Is in the Literature

What is in the Literature focuses on chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), a neuropathy with challenges in diagnosis and treatment. A recent revision of diagnostic criteria (EFN/PNS criteria) has helped define clinical features of typical and atypical variants and what is not considered CIDP. Initiating pathologic factors is not known for typical CIDP or variants. New treatment approaches are based on immunologic mechanisms. Rare patients with a CIDP-like clinical pattern are found to have antibodies to proteins at and around the node of Ranvier and are not considered to be CIDP but a nodal-paranodopathy. Although occurring mainly in adults, CIDP also occurs in children. CIDP may have clinical and electrodiagnostic features that overlap with hereditary neuropathies, and the latter might show some response to treatment. Articles published in the past year that address these issues are discussed in this review.

Association of plasma neurofilament light chain with disease activity in chronic inflammatory demyelinating polyradiculoneuropathy

BACKGROUND AND PURPOSE

This study was undertaken to explore associations between plasma neurofilament light chain (pNfL) concentration (pg/ml) and disease activity in patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and examine the usefulness of pNfL concentrations in determining disease remission.

METHODS

We examined pNfL concentrations in treatment-naïve CIDP patients (n = 10) before and after intravenous immunoglobulin (IVIg) induction treatment, in pNfL concentrations in patients on maintenance IVIg treatment who had stable (n = 15) versus unstable disease (n = 9), and in clinically stable IVIg-treated patients (n = 10) in whom we suspended IVIg to determine disease activity and ongoing need for maintenance IVIg. pNfL concentrations in an age-matched healthy control group were measured for comparison.

RESULTS

Among treatment-naïve patients, pNfL concentration was higher in patients before IVIg treatment than healthy controls and subsequently reduced to be comparable to control group values after IVIg induction. Among CIDP patients on IVIg treatment, pNfL concentration was significantly higher in unstable patients than stable patients. A pNFL concentration > 16.6 pg/ml distinguished unstable treated CIDP from stable treated CIDP (sensitivity = 86.7%, specificity = 66.7%, area under receiver operating characteristic curve = 0.73). Among the treatment withdrawal group, there was a statistically significant correlation between pNfL concentration at time of IVIg withdrawal and the likelihood of relapse (r = 0.72, p < 0.05), suggesting an association of higher pNfL concentration with active disease.

CONCLUSIONS

pNfL concentrations may be a sensitive, clinically useful biomarker in assessing subclinical disease activity.

Versorgungssituation von CIDP-Patienten in neun deutschen Zentren des Neuritis Netzes

Hintergrund

Die Diagnose und Behandlung von Patienten mit immunvermittelten Polyneuropathien ist aufgrund der Heterogenität der Erkrankungen herausfordernd.

Ziel der Arbeit

Ein aktueller epidemiologischer Überblick über die Versorgungssituation von Patienten mit immunvermittelten Polyneuropathien innerhalb des deutschen Neuritis-Netzwerks „Neuritis Netz“.

Material und Methoden

Es erfolgte eine Umfrage in neun deutschen neurologischen Zentren, die auf die Betreuung von Patienten mit Immunneuropathie spezialisiert sind. Wir erfassten Diagnose, Vorgehen in der Diagnostik und Nachsorge, typische Symptome bei Manifestation und im Krankheitsverlauf sowie Therapiedaten.

Ergebnisse

Die Erhebung umfasst Daten von 1529 jährlich behandelten Patienten mit Immunneuropathien, 1320 davon mit chronisch inflammatorisch demyelinisierender Polyneuropathie (CIDP). Die Diagnostik umfasste fast immer Lumbalpunktionen sowie Elektroneuro- und -myografien entsprechend den aktuellen Leitlinien. Der Einsatz von Ultraschall, Biopsie und MRT war unterschiedlich. Wichtigster klinischer Parameter zum Therapiemonitoring in allen Zentren war die motorische Funktion in den klinischen Nachuntersuchungen. Zur Erhaltungstherapie wurde bei rund 15 % der Patienten ein breites Spektrum unterschiedlicher Immunsuppressiva eingesetzt.

Diskussion

Die Studie liefert wichtige epidemiologische Daten zur aktuellen Versorgungsituation von Patienten mit Immunneuropathien in Deutschland. Die Weiterentwicklung spezifischer Empfehlungen zur Therapie und Nachverfolgung von CIDP-Patienten ist notwendig, um einen einheitlichen Standard der Patientenversorgung zu gewährleisten. Dieses wird durch die strukturierte Zusammenarbeit von Exzellenzzentren wie dem deutschen Neuritis Netz erheblich unterstützt.

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.