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Although there is no “best” way to determine which route of administration is best, healthcare providers are uniquely positioned to educate patients and help them make the best decision.
With intravenous immunoglobulin (IVIG) and subcutaneous immunoglobulin (SCIG) available for patients with chronic inflammatory demyelinating polyneuropathy (CIDP), researchers have identified a need for information to help clinicians and patients choose the optimal approach.
A recently published article in the Journal of Neurological Sciences considerations described for pharmacokinetics, administration procedures, adverse events, patient variables, and cost.
CIDP is an acquired neurological condition characterized by weakness and impaired sensory function progressing over 2 months or more, loss or reduction of deep tendon reflexes, and electrophysiological signs of peripheral nerve demyelination. Effective diagnosis and treatment early in the disease are essential to avoid irreversible disability.
IVIG is used both as a first-line treatment and as a maintenance treatment option for patients with CIDP. Other first-line treatments with proven efficacy include corticosteroids and plasmapheresis. Additionally, the FDA approved SCIG in 2018 for patients with CIDP, opening new treatment options for maintenance therapy. However, researchers have identified a need for more information on the differences between IVIG and SCIG.
The efficacy of IVIG has been established in 5 randomized placebo-controlled trials conducted between 1993 and 2008. Based on these trials, clinicians have high-quality evidence that IVIG is safe and effective for the induction and maintenance treatment of CIDP. In particular, the ICE study found that patients receiving IVIG reported significant improvements in the physical functioning, physical role, social functioning, and mental health domains of a quality of life assessment.
The efficacy and safety of SCIG as maintenance therapy was established in the Polyneuropathy and Treatment with Hizentra (PATH) study of 172 IVIG-dependent patients with CIDP. Participants were randomly assigned to receive SCIG 0.2 g/kg per week, which is 40% less than the IVIG trial, or 0.4 g/kg per week, which is 20% more than the IVIG trial , or placebo for 24 weeks.
The primary endpoint was the proportion of patients who relapsed or withdrew from the study for any reason during the 24-week treatment period. Those who relapsed during SC treatment were rescued with IVIG and arrested.
In the placebo arm, 63% of patients relapsed or withdrew from the study, compared to 39% in the low dose group and 33% in the high dose group. When only relapse was considered, 56% of placebo-treated patients relapsed over the 24-week period, compared with 33% of low-dose patients and 19% of high-dose patients.
Among patients receiving SCIG treatment, 53% reported a preference for SCIG compared to 39% of patients in the placebo group. Reasons for this preference included increased independence and fewer adverse effects (AEs). Eighteen percent of patients receiving SCIG said they preferred their previous IVIG treatment.
It is also important to consider pharmacokinetics, AE profiles, site of care, patient preference variables, and economics.
After an IVIG infusion, the concentration of immunoglobulin G (IgG) peaks within minutes and decreases approximately by half over the next 2-3 days. Following this rapid equilibration, IgG is catabolized with first-order kinetics and a half-life of 21-30 days.
It is important to note that the optimal pharmacokinetic parameters for the treatment of CIDP are unknown. Although pharmacokinetic parameters are important considerations for optimizing immunoglobulin efficacy, the authors stated that many questions remain.
The key principle of pharmacokinetics is that the dose and treatment intervals needed to achieve and maintain a given clinical response vary widely from individual to individual. Identifying these differences can help clinicians take advantage of the differences between SCIG and IVIG pharmacokinetics.
The most common IVIG-related systemic AEs are headache and nausea. Many IVIG AEs can be managed with adequate hydration and medication, such as antihistamines, acetaminophen, and corticosteroids, as well as slowing the infusion rate or switching to another IVIG preparation. Systemic AEs of SCIG are similar, although the frequency and severity of SCIG infusions are generally less than with IVIG.
Since SCIG requires no IV access, patients with difficult IV access may be good candidates for SCIG. The most common AE reported and unique to SCIG is local reactions at the infusion site, such as redness, itching or swelling.
Currently, patients with CIDP can receive immunoglobulin therapy in a hospital clinic, doctor’s office, stand-alone infusion clinic, or at home. Although IVIG is supervised by a nurse, most SCIG maintenance regimens can be administered by the patient or caregiver without the need for other medical support personnel. Patients can travel with their SCIG, eliminating the need to be near an infusion center or other facility at a fixed interval.
Surveys have also revealed that patients appreciate the convenience, autonomy and home administration associated with the SCIG. However, the weekly handling of needles and medical equipment without the help of a trained healthcare professional can be limiting for some patients, especially those with upper limb disabilities.
Finally, the authors noted that the economics of IVIG versus SCIG for CDIP are not well understood. A hypothetical cost analysis showed that the low-dose SCIG regimen resulted in a savings of $900 over the IVIG regimen ($8,248 vs. $9,131 over 3 weeks). However, when the high-dose SCIG regimen is required, the costs to the payer would almost double. These results are also consistent with results from European analyses, demonstrating that the cost of the immunoglobulin formulation is often the main driver of the overall cost of treating CIDP, according to the study.
With all of these considerations in mind, the authors emphasized the need to accommodate individual patient needs and preferences. The decision to use SCIG or IVIG should be tailored to the patient’s disease characteristics, treatment goals, and lifestyle. Although there is no “best” way to determine which route of administration is best, healthcare providers are uniquely positioned to educate patients and help them make the best decision.
REFERENCE
Allen JA, Gelinas DF, Freimer M, Runken MC and Wolfe GI. Administration of immunoglobulins for the treatment of CIDP: IVIG or SCIG? Journal of Neurological Sciences; November 9, 2019. Accessed September 13, 2022. https://www.jns-journal.com/article/S0022-510X(19)30429-0/fulltext
