Minimum clinically important difference analysis confirms the efficacy of IgPro10 in CIDP: the PRIMA trial

Minimal Clinically Important Difference (MCID) in Patient-Reported Outcome Measures for Neurological Conditions: Review of Concept and Methods

The concept of the minimal clinically important difference (MCID) emerged from the recognition that statistical significance alone is not enough to determine the clinical relevance of treatment effects in clinical research. In many cases, statistically significant changes in outcomes may not be meaningful to patients or may not result in any tangible improvements in their health. This has led to a growing emphasis on the importance of measuring patient-reported outcome measures (PROMs) in clinical trials and other research studies, in order to capture the patient perspective on treatment effectiveness. MCID is defined as the smallest change in scores that is considered meaningful or important to patients. MCID is particularly important in fields such as neurology, where many of the outcomes of interest are subjective or based on patient-reported symptoms. This review discusses the challenges associated with interpreting outcomes of clinical trials based solely on statistical significance, highlighting the importance of considering clinical relevance and patient perception of change. There are two main approaches to estimating MCID: anchor-based and distribution-based. Anchor-based approaches compare change scores using an external anchor, while distribution-based approaches estimate MCID values based on statistical characteristics of scores within a sample. MCID is dynamic and context-specific, and there is no single 'gold standard' method for estimating it. A range of MCID thresholds should be defined using multiple methods for a disease under targeted intervention, rather than relying on a single absolute value. The use of MCID thresholds can be an important tool for researchers, neurophysicians and patients in evaluating the effectiveness of treatments and interventions, and in making informed decisions about care.

Role of altered IL-33/ST2 immune axis in the immunobiology of Guillain-Barré syndrome

BACKGROUND

IL-33/ST2 immune axis plays crucial roles in infection and immunity. A dysregulated IL-33/ST2 axis can induce autoimmune reaction and inflammatory responses. Guillain-Barré Syndrome (GBS) is an acute peripheral neuropathy, mostly caused by post-infection autoimmunity. The role of IL-33/ST2 axis is not known in GBS. This study aimed to explore the role of IL-33/ST2 axis in GBS.

METHODS

Three single nucleotide polymorphisms (SNPs) of Il33 gene (rs16924159; rs7044343; rs1342336) and three SNPs of Il1rl1 gene (rs10192157, rs1041973, rs10206753), coding for ST2 were genotyped in 179 GBS patients and 186 healthy controls by TaqMan Allelic Discrimination Assay. Plasma levels of IL-33 and sST2 were measured in a subset of GBS (n=80) and healthy controls (n=80) by ELISA.

RESULTS

The frequencies of CC genotype of rs10192157 (p=0.043) and TT genotype of rs10206753 (p=0.036) SNPs of Il1rl1 gene differed significantly between GBS patients and healthy subjects. Gene-gene interaction between Il33 and Il1rl1 genes also conferred significant risk to GBS. In addition, the plasma sST2 levels were significantly elevated in GBS patients compared to healthy subjects (24,934.31 ± 1.81 pg/ml vs. 12,518.97 ± 1.51 pg/ml, p<0.001). Plasma sST2 levels showed a significant correlation with the disability scores at the peak of neurological deficit in GBS patients.

CONCLUSIONS

IL-33/ST2 axis is suggested to influence the immunopathogenesis of GBS. Genetic variants of Il1rl1 gene might serve as a risk determinant of GBS and plasma sST2 levels might emerge as a biomarker of severity of GBS, if replicated further by other studies.

Variations within Toll-like receptor (TLR) and TLR signalling pathway-related genes and their synergistic effects on the risk of Guillain-Barré Syndrome

Guillain-Barré Syndrome (GBS) is the commonest postinfectious polyradiculopathy. Though genetic background of the host seems to play an important role in the susceptibility to GBS, genes conferring major risk are not yet known. Dysregulation of Toll-like receptor (TLR) molecules exacerbates immune-inflammatory responses and the genetic variations within TLR pathway-related genes contribute to differential risk to infection. To delineate the impact of genetic variations within TLR2, TLR3, and TLR4 genes and TLR signaling pathway-related genes such as MyD88, TRIF, TRAF3, TRAF6, IRF3, NFκβ1, and IκBα on risk of developing GBS. Fourteen polymorphisms located within TLR2 (rs3804099; rs111200466), TLR3 (rs3775290; rs3775291), TLR4 (rs1927911, rs11536891), MyD88 (rs7744, rs4988453), TRIF (rs8120 TRAF3 (rs12147254), TRAF6 (rs4755453), IRF3 (rs2304204), NFκβ1 (rs28362491) and IκBα (rs696) genes were genotyped in 150 GBS patients and 150 healthy subjects either by PCR-RFLP or TaqMan Allelic Discrimination Assay. Genotypes of two polymorphic variants, Del/Del of rs111200466 Insertion and Deletion (INDEL) polymorphism of TLR2 gene and TT of rs3775290 single nucleotide polymorphism (SNP) of TLR3 gene had significantly higher frequencies among GBS patients, while the frequencies of TT genotype of rs3804099 of TLR2 gene and TT genotype of rs11536891 SNP of TLR4 gene were significantly higher in controls. Gene-gene interaction study by Multifactor Dimensionality Reduction (MDR) analysis also suggested a significant combined effect of TLR2, and NFκβ1 genes on the risk of GBS. The SNPs in the IκBα and IRF3 genes correlated with severity of GBS. The genes encoding TLRs and TLR signalling pathway-related molecules could serve as crucial genetic markers of susceptibility and severity of GBS. This article is protected by copyright. All rights reserved.

Prognostic value of neurofilament light chain in chronic inflammatory demyelinating polyneuropathy

Chronic inflammatory demyelinating polyneuropathy is a neuroinflammatory disorder with considerable variation in clinical phenotype, disease progression and therapy response among patients. Recently, paranodal antibodies associated with poor response to intravenous immunoglobulin therapy and more aggressive disease course have been described in small subsets of patients, but reliable serum-based prognostic biomarkers are not yet available for the general population. In current retrospective longitudinal study, we utilized logistic regression models to investigate the associations of serum neurofilament light chain levels with 1-year disease progression and therapy response during follow-up in chronic inflammatory demyelinating polyneuropathy. One-year disease progression was defined as a decrease of four or more points (the minimal clinically important difference) on an 80-point Medical Research Council sum-score scale 1 year after sampling. Patients who, compared to treatment received at time of sampling, required therapy switch during follow-up due to insufficient effect were classified as non-responders. Serum neurofilament light chain was measured by electrochemiluminescence assay in clinical residual serum samples of 76 patients diagnosed with probable (13 patients) or definite (63 patients) chronic inflammatory demyelinating polyneuropathy according to European Federation of Neurological Societies/Peripheral Nerve Society diagnostic criteria. Eleven (15%) patients were female, and the mean (standard deviation) cohort age was 61.5 (11.7) years. In both univariate and multivariable (including demographics) models, elevated serum neurofilament light chain harboured increased odds for 1-year disease progression (respectively odds ratio, 1.049; 95% confidence interval, 1.022-1.084 and odds ratio, 1.097; 95% confidence interval, 1.045-1.169; both P = 0.001). Patients with levels above the median cohort neurofilament light chain level (28.3 pg/ml) had largely increased odds of 1-year disease progression (univariate: odds ratio, 5.597; 95% confidence interval, 1.590-26.457; P = 0.01; multivariable: odds ratio, 6.572; 95% confidence interval, 1.495-39.702; P = 0.02) and of insufficient treatment response (univariate: odds ratio, 4.800; 95% confidence interval, 1.622-16.442; P = 0.007; multivariable: odds ratio, 6.441; 95% confidence interval, 1.749-29.357; P = 0.009). In a combined approach analysis, patients with levels above median cohort serum neurofilament light chain level reported strongly increased odds of demonstrating 1-year disease progression and/or therapy non-response during follow-up (univariate: odds ratio, 6.337; 95% confidence interval, 2.276-19.469; P < 0.001; multivariable: odds ratio, 10.138; 95% confidence interval, 2.801-46.404; P = 0.001). These results show that in various logistic regression models, serum neurofilament light chain was associated with both 1-year disease progression and therapy response during follow-up in chronic inflammatory demyelinating polyneuropathy. Hence, our findings warrant further prospective research regarding the value of neurofilament light chain as potential prognostic biomarker in chronic inflammatory demyelinating polyneuropathy.

Monitoring Clinical Course and Treatment Response in Chronic Inflammatory Demyelinating Polyneuropathy During Routine Care: A Review of Clinical and Laboratory Assessment Measures

Importance

Identifying clinical change in many neurologic diseases, including chronic inflammatory demyelinating polyneuropathy (CIDP), can be challenging. At the same time, how change is defined heavily influences a patient's diagnostic and treatment pathway. It can be especially problematic when equivocal subjective observations are interpreted as clinically meaningful and then used to make diagnostic and treatment decisions. Change in clinical trials is strictly defined by a preselected metric, but there is a perception that formal outcomes collection during routine clinical care is neither feasible nor necessary. Given the importance placed on how change is interpreted, there is a need to select assessments that can be applied to routine care that are representative of the neurologic disease state.

Observations

For an outcome measure to be useful during clinical trials, it must have good reliability, validity, be responsive to change, and have clinical meaning. To be useful during routine clinical care, the assessment must additionally be easy to collect without the need for extensive training or equipment and should provide an immediately available result that can be rapidly quantified and interpreted. Chronic inflammatory demyelinating polyneuropathy is clinically heterogeneous and so is best evaluated with a diverse group of assessment tools. Assessing strength impairment, disability, and quality of life is ideally suited for everyday practice when caring for patients with CIDP. While electrophysiologic studies, imaging, cerebrospinal fluid, and nodal/paranodal antibodies can provide diagnostic data, they are less practical and helpful longitudinal assessment tools.

Conclusions and Relevance

Sound clinimetric outcome measures in CIDP are widely available and have the potential to help clinicians objectify treatment response and disease progression. Such data are critically important when justifying the need for ongoing or periodic immunotherapy, documenting relapse or deterioration, or providing reassurance of disease improvement, stability, or remission.

Efficacy and safety of IVIG in CIDP: Combined data of the PRIMA and PATH studies

Intravenous immunoglobulin (IVIG) is a potential therapy for chronic inflammatory demyelinating polyneuropathy (CIDP). To investigate the efficacy and safety of the IVIG IgPro10 (Privigen) for treatment of CIDP, results from Privigen Impact on Mobility and Autonomy (PRIMA), a prospective, open‐label, single‐arm study of IVIG in immunoglobulin (Ig)‐naïve or IVIG pre‐treated subjects (NCT01184846, n = 28) and Polyneuropathy And Treatment with Hizentra (PATH), a double‐blind, randomized study including an open‐label, single‐arm IVIG phase in IVIG pre‐treated subjects (NCT01545076, IVIG restabilization phase n = 207) were analyzed separately and together (n = 235). Efficacy assessments included change in adjusted inflammatory neuropathy cause and treatment (INCAT) score, grip strength and Medical Research Council (MRC) sum score. Adverse drug reactions (ADRs) and ADRs/infusion were recorded. Adjusted INCAT response rate was 60.7% in all PRIMA subjects at Week 25 (76.9% in IVIG pre‐treated subjects) and 72.9% in PATH. In the pooled cohort (n = 235), INCAT response rate was 71.5%; median time to INCAT improvement was 4.3 weeks. No clear demographic differences were noticed between early (responding before Week 7, n = 148) and late responders (n = 21). In the pooled cohort, median change from baseline to last observation was −1.0 (interquartile range −2.0; 0.0) point for INCAT score; +8.0 (0.0; 20.0) kPa for maximum grip strength; +3.0 (1.0; 7.0) points for MRC sum score. In the pooled cohort, 271 ADRs were reported in 105 subjects (44.7%), a rate of 0.144 ADRs per infusion. This analysis confirms the efficacy and safety of IgPro10, a recently FDA‐approved IVIG for CIDP, in a population of mainly pre‐treated subjects with CIDP [Correction added on 14 March 2019 after first online publication: the INCAT response rate has been corrected.].