Long-term treatment with subcutaneous immunoglobulin in patients with chronic inflammatory demyelinating polyradiculoneuropathy: a follow-up period up to 7 years

Subcutaneous immunoglobulins (SCIG) for chronic inflammatory demyelinating polyneuropathy (CIDP): A comprehensive systematic review of clinical studies and meta-analysis

BACKGROUND

Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) presents significant treatment challenges due to its chronic nature, varied clinical presentations, and rarity. Subcutaneous immunoglobulin (SCIG) has emerged as a maintenance therapy, offering potential advantages in administration and patient experience over the previously recognized intravenous immunoglobulin (IVIG).

METHODS

We included all clinical studies involving CIDP patients treated with SCIG from eleven databases up to March 2024.

RESULTS

50 clinical studies were included in the systematic review, with 22 involved in the meta-analysis. These studies offer clinical data on around 1400 CIDP patients. Almost all studies considered SCIG a maintenance therapy, with the majority of results suggesting it as a viable substitute that may offer comparable or enhanced advantages. Studies covered aspects such as efficacy, safety, quality of life, practicality, economic evaluation, and patient preference. Meta-analysis showed SCIG significantly improved muscle strength and sensory function, had fewer and milder side effects, reduced relapse rates, and received a strong preference.

CONCLUSIONS

Findings suggest that SCIG for CIDP maintenance not only provides a more feasible alternative, with economic evaluations showing considerable cost reductions over time, and patient preference for SCIG being pronounced, but may also deliver comparable or superior health outcomes. Ongoing research lines on formulations, techniques, and direct comparative studies are critical to further illuminate, enhance, and expand SCIG's role in treatment.

Intravenous Immunoglobulin Initiation in Patients with Chronic Inflammatory Demyelinating Polyradiculoneuropathy: A US Claims-based Cohort Study

INTRODUCTION

Intravenous immunoglobulin (IVIG) is recommended as first-line therapy for chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), an immune-mediated neuropathy. The clinical profile of patients with CIDP newly initiating IVIG is poorly characterized. This claims-based cohort study describes characteristics of US patients with CIDP initiating IVIG treatment.

METHODS

Adult immunoglobulin (IG)-naïve patients with CIDP diagnosed between 2008 and 2018 and a subgroup of patients subsequently initiating IVIG were identified in the Merative MarketScan Research Databases. Demographics, clinical characteristics, and diagnostic procedures were described for patients initiating IVIG.

RESULTS

Of 32,090 patients with CIDP identified, 3975 (mean age 57 years) subsequently initiated IVIG. In the 6 months prior to IVIG initiation, diagnoses of comorbidities including neuropathy (75%), hypertension (62%), and diabetes (33%) were frequent, as were CIDP features/symptoms/markers of functional status including chronic pain (80%), difficulty walking (30%), and weakness (30%). CIDP-related laboratory/diagnostic procedures were performed in approximately 20- > 40% of patients in the 3 months prior to IVIG initiation (63.7% underwent electrodiagnostic/nerve conduction testing in the 6 months prior to IVIG initiation). Patient characteristics by initial IVIG product differed only in IVIG initiation year, US geographic region, and insurance type. Comorbidities, CIDP severity or functional status markers, and other clinical variables were generally well balanced across initial IVIG product groups.

CONCLUSION

A heavy burden of symptoms, comorbidities, and diagnostic testing exists in patients with CIDP initiating IVIG. Characteristics of patients with CIDP initiating different IVIG products are well balanced, suggesting an absence of clinical or demographic determinants underlying IVIG selection.

Clinical and Neurophysiological Follow-Up of Chronic Inflammatory Demyelinating Polyneuropathy Patients Treated with Subcutaneous Immunoglobulins: A Real-Life Single Center Study

BACKGROUND

chronic idiopathic demyelinating polyneuropathy (CIDP) is an acquired, immune-mediated neuropathy characterized by weakness, sensory symptoms and significant reduction or loss of deep tendon reflexes evolving over 2 months at least, associated with electrophysiological evidence of peripheral nerve demyelination. Recently, subcutaneous immunoglobulins (SCIg) have been introduced in clinical practice as a maintenance therapy for CIDP; nevertheless, electrophysiological and efficacy data are limited.

METHODS

to evaluate SCIg treatment efficacy, we retrospectively reviewed data from 15 CIDP patients referring to our clinic, receiving SCIg treatment and who performed electrophysiological studies (NCS) and clinical scores (MRC sumscore, INCAT disability score and ISS) before starting the treatment and at least one year after.

RESULTS

NCS showed no significant changes before and during treatment for all the nerves explored. Clinical scores did not significantly change between evaluations. Correlation analysis evidenced a positive correlation of cMAPs distal amplitude with MRC sumscore and a trend of negative correlation with the INCAT disability score.

CONCLUSIONS

SCIg maintenance therapy preserves nerve function in CIDP with a good efficacy and safety. Treatment effectiveness can be assessed with ENG, which represents a useful instrument in the follow-up and prognostic assessment of CIDP.

Update on therapy of chronic immune-mediated neuropathies

Chronic immune-mediated neuropathies, including chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), neuropathies associated with monoclonal gammopathy, and multifocal motor neuropathy (MMN), are a group of disorders deemed to be caused by an immune response against peripheral nerve antigens. Several immune therapies have been reported to be variably effective in these neuropathies including steroids, plasma exchange, and high-dose intravenous (IVIg) or subcutaneous (SCIg) immunoglobulins. These therapies are however far from being invariably effective and may be associated with a number of side effects leading to the use of immunosuppressive agents whose efficacy has not been so far confirmed in randomized trials. More recently, new biological agents, such as rituximab, have proved to be effective in patients with neuropathy associated with IgM monoclonal gammopathy and are currently tested in CIDP.

Disparate healthcare access and telehealth-based hybrid consultations during the COVID-19 pandemic

BACKGROUND: The coronavirus disease-2019 pandemic led to rapid expansion of telehealth services. This was speculated to improve healthcare access among underserved populations, including individuals unable to take time off work or arrange transportation. OBJECTIVE: We completed a quality improvement project to evaluate the feasibility of hybrid consultations that combined televisits and abbreviated in-person visits for neuromuscular referrals. METHODS: Using a censoring date of August 5, 2021, we reviewed all outpatient neuromuscular consultations from August 5, 2020 to February 5, 2021. For both hybrid and traditional in-person consultations, we reviewed no-show rates, completion rates of ordered diagnostic workup, and billing codes. For hybrid consultations only, we also reviewed intervals between initial televisit and subsequent examination and rates of video-enhanced versus audio-only televisits. RESULTS: During the study period, we completed 153 hybrid and 59 in-person new-patient consultations (no-show rates 9% and 27% respectively.) For hybrid consultations, 77% and 73% of laboratory and imaging studies were completed respectively, compared to 89% and 91% for in-person consultations. For hybrid visits, average RVUs (a marker for reimbursement) per consultation depended on whether audio-only televisits were billed as telephone calls or E/M visits per insurance payer rules, while video-enhanced televisits were uniformly billed as E/M visits. This resulted in average RVUs between 2.09 and 2.26, compared to 2.30 for in-person consultations. CONCLUSIONS: Telehealth-based hybrid neuromuscular consultations are feasible with minor caveats. However, the future of telehealth may be restricted by decreasing reimbursement rates particularly for audio-only televisits, limiting its potential to improve healthcare access.

CIDP: Current Treatments and Identification of Targets for Future Specific Therapeutic Intervention

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an acquired immune-mediated inflammatory disorder of the peripheral nervous system. This clinically heterogeneous neurological disorder is closely related to Guillain–Barré syndrome and is considered the chronic counterpart of that acute disease. Currently available treatments are mostly empirical; they include corticosteroids, intravenous immunoglobulins, plasma exchange and chronic immunosuppressive agents, either alone or in combination. Recent advances in the understanding of the underlying pathogenic mechanisms in CIDP have brought a number of novel ways of possible intervention for use in CIDP. This review summarizes selected pre-clinical and clinical findings, highlights the importance of using adapted animal models to evaluate the efficacy of novel treatments, and proposes the outlines of future directions to ameliorate the conditions of patients with CIDP.

Subcutaneous immunoglobulin treatment for chronic inflammatory demyelinating polyneuropathy

Immunoglobulin G (IgG) therapy is an established long‐term treatment in chronic inflammatory demyelinating polyneuropathy (CIDP) that is commonly administered intravenously (IVIg). The subcutaneous immunoglobulin (SCIg) administration route is a safe and effective alternative option, approved by the United States Food and Drug Administration (FDA) in 2018, for maintenance treatment of adults with CIDP. Physicians and patients alike need to be aware of all their treatment options in order to make informed decisions and plan long‐term treatment strategies. In this review, we collate the evidence for SCIg in CIDP from all published studies and discuss their implications and translation to clinical practice. We also provide guidance on the practicalities of how and when to transition patients from IVIg to SCIg and ongoing patient support. Evidence suggests that IVIg and SCIg have comparable long‐term efficacy in CIDP. However, SCIg can provide additional benefits for some patients, including no requirement for venous access or premedication, and reduced frequency of systemic adverse events. Local‐site reactions are more common with SCIg than IVIg, but these are mostly well‐tolerated and abate with subsequent infusions. Data suggest that many patients prefer SCIg following transition from IVIg. SCIg preference may be a result of the independence and flexibility associated with self‐infusion, whereas IVIg preference may be a result of familiarity and reliance on a healthcare professional for infusions. In practice, individualizing maintenance dosing based on disease behavior and determining the minimally effective IgG dose for individuals are key considerations irrespective of the administration route chosen.

A systematic review of population pharmacokinetic analyses of polyclonal immunoglobulin G therapy

BACKGROUND

Population pharmacokinetics (popPK) using the nonlinear mixed-effect (NLME) modeling approach is an essential tool for guiding dose individualization. Several popPK analyses using the NLME have been conducted to characterize the pharmacokinetics of immunoglobulin G (IgG).

OBJECTIVE

To summarize the current information on popPK of polyclonal IgG therapy.

METHOD

A systematic search was conducted in the PubMed and Web of Science databases from inception to December 2020. Additional relevant studies were also included by reviewing the reference list of the reviewed articles. All popPK studies that employed the NLME modeling approach were included and data were synthesized descriptively.

RESULTS

This review included seven studies. Most of the popPK models were developed in patients with primary immunodeficiency (PID). IgG pharmacokinetics was described as a two-compartment model in five studies, while it was described as a one-compartment model in two other studies. Among all tested covariates, weight was consistently identified as a significant predictor for clearance (CL) of IgG. Whereas, weight and disease type were found to be significant predictors for the volume of distribution in central compartment (Vc). In a typical 70 kg adult, the median estimated values of Vc and CL were 4.04 L and 0.144 L/day, respectively. The between subject variability of Vc was considered large. Only two studies evaluated their models using external data.

CONCLUSIONS

Seven popPK studies of IgG were found and discussed, with only weight being a significant covariate across all studies. Future studies linking pharmacokinetics with pharmacodynamics in PID and other patient populations are required.

Long-term treatment with subcutaneous immunoglobulin in multifocal motor neuropathy

Multifocal motor neuropathy (MMN) is a rare disease with a prevalence of less than 1 per 100,000 people. Intravenous immunoglobulin (IVIG) therapy, performed for a long-term period, has been demonstrated able to improve the clinical picture of MMN patients, ameliorating motor symptoms and/or preventing disease progression. Treatment with subcutaneous immunoglobulin (SCIg) has been shown to be as effective as IVIG. However, previously published data showed that follow-up of MMN patients in treatment with SCIg lasted no more than 56 months. We report herein the results of a long-term SCIg treatment follow up (up to 96 months) in a group of 8 MMN patients (6 M; 2F), previously stabilized with IVIG therapy. Clinical follow-up included the administration of Medical Research Council (MRC) sum-score, the Overall Neuropathy Limitation Scale (ONLS) and the Life Quality Index questionnaire (LQI) at baseline and then every 6 months. Once converted to SCIg, patients’ responsiveness was quite good. Strength and motor functions remained stable or even improved during this long-term follow-up with benefits on walking capability, resistance to physical efforts and ability in hand fine movements.

Subcutaneous immunoglobulin dose titration to clinical response in inflammatory neuropathy

INTRODUCTION

Individualized dosing is an established approach in intravenous immunoglobulin (IVIg) treatment for inflammatory neuropathies. There is less experience in effective dosing strategies for subcutaneous (SC) immunoglobulin.

METHODS

We conducted a retrospective cohort study of patients with inflammatory neuropathies transferring from IVIg to SCIg in two UK peripheral nerve services. I-RODS and grip strength were used to measure outcome. Dose and clinical progress were documented at 1 year and at last review.

RESULTS

44/56 patients remained on maintenance SCIg beyond 1 year (mean 3.3 years, range 1-9 years) with stable clinical outcomes. Clinical deteriorations were corrected by small increases in SCIg dose in 20 patients at 1 year, a further 9 requiring subsequent further up-titrations. Sixteen tolerated dose reduction. Mean dose change was + 2.4% from baseline. Two patients required IVIg bolus rescue (2 g/kg). Three patients successfully discontinued Ig therapy. Nine patients returned to IVIg due to clinical relapse or patient preference. Overall tolerance was good.

DISCUSSION

Dose titration to clinical response is an effective approach in SCIg maintenance therapy.

Home-based subcutaneous immunoglobulin for chronic inflammatory demyelinating polyneuropathy patients: A Swiss cost-minimization analysis

PURPOSE

To compare the cost of two patient management strategies with similar efficacies for chronic inflammatory demyelinating polyneuropathy (CIDP) patients in the chronic phase: hospital-based IV immunoglobulin G (IVIg) and home-based subcutaneous immunoglobulin G (SCIg) associated with an interprofessional drug therapy management programme (initial training and follow-up).

METHODS

A 48-week model-based cost-minimization analysis from a societal perspective was performed. Resources included immunoglobulin (IVIg: 1 g/kg/3 weeks; SCIg: 0.4 g/kg/week initially and 0.2 g/kg/week in the maintenance phase), hospital charges, time of professionals, infusion material, transport and losses of productivity for patients. Costs were expressed in Swiss francs (CHF) (1 CHF = 0.93€ = US$1.10, www.xe.com, 2020/10/28).

RESULTS

The total costs of IVIg were higher than those of SCIg for health insurance and other payers: 114,747 CHF versus 86,558 CHF and 8,762 CHF versus 2,401 CHF, respectively. The results were sensitive to the immunoglobulin doses, as this was the main cost driver. The SCIg daily cost in the initial phase was higher for health insurance than hospital-based IVIg was, but the additional costs were compensated during the maintenance phase (from week 28). The professional costs associated with the switch were not fully covered by the insurance and were borne by the pharmacist and the nurse.

CONCLUSIONS

SCIg for CIDP patients reinforced by an interprofessional drug therapy management programme may be a cost-effective and sustainable alternative to IVIg in the Swiss system context. From an economic perspective, this therapy alternative should be more widely supported by healthcare systems and proposed to eligible patients by professionals.