What Patients Can Expect From IVIG and SCIG Replacement Therapy

IVIG or SCIG may help people with antibody deficiencies who cannot make effective immunoglobulin, particularly when they have had multiple severe bacterial infections. The therapy provides regular IgG infusions, with the route, setting, and training arranged with the care team.

Why a care team may consider replacement therapy

Many people with predominantly antibody deficiencies cannot produce effective immunoglobulin. A pragmatic review in The Journal of Allergy and Clinical Immunology: Global describes regular IgG infusions as a way to replenish low, absent, or ineffective IgG. The authors call this immunoglobulin replacement therapy, or IgRT.

On The Allergist podcast from CSACI, Benjamin Prince of Nationwide Children's Hospital says IVIG or subcutaneous immunoglobulin is generally reserved for patients who have had multiple severe bacterial infections or very bad infections. He also questions testing when no available intervention, such as prophylactic antibiotics or immunoglobulin replacement, would benefit the patient.

For many secondary immunodeficiencies, Samira Jeimy of Western University says there is no single cutoff for starting replacement therapy. Jeimy describes the decision as a collaboration among the patient, immunology team, and other specialties. For decisions about an individual's treatment, patients should talk with their own doctor.

Where infusions may happen

IVIG is given into a vein. In a survey of patients with primary and secondary immunodeficiencies, home was the most common reported setting for IVIG: 47% received infusions at home, 37% at an infusion center, and 11% in a hospital. These percentages describe the surveyed patients' treatment settings.

Home therapy can involve a specialty pharmacy delivering immunoglobulin and arranging infusion support. In testimony to the Oregon Senate, an Immune Deficiency Foundation representative said that for people with primary immunodeficiency, therapy is shipped to the home through a specialty pharmacy or administered in a clinical setting. The representative said it is not picked up at a local pharmacy.

A National Home Infusion Association article cited analyses estimating that about 83,000 patients per year receive immune globulin therapy at home. That estimate reflects home infusion across the patient population discussed in the article.

SCIG may also be administered by a nurse in a clinic. A PLOS ONE study of nurse-administered SCIG in a hospital infusion clinic found that total clinic time, infusion time, and nursing time were similar to IVIG, with comparably high patient satisfaction. The result describes the hospital clinic model in that study.

How IVIG and SCIG feel different in the body

The routes affect how immunoglobulin enters the body. Michelle Greer explains on an IG Living podcast that IVIG goes into a vein, so its effects and reactions can be more immediate and systemic. SCIG goes into tissue under the skin and is absorbed more slowly, with effects occurring over time.

Some SCIG products use hyaluronidase to facilitate delivery. A review of earlier phase 3 research in people with primary immunodeficiency reports that facilitated SCIG 10% was effective at dosing intervals similar to IVIG after a dose ramp-up, with fewer systemic adverse events. The ramp-up is part of the approach described in those studies.

The amount infused, number of infusion sites, and schedule can vary. A pragmatic review of immunoglobulin replacement studies notes variation in individual dosing and the number of infusion sites used. The care team can explain the plan for the specific product and route.

What happens when starting or switching to SCIG

A first dose may be given in a supervised setting when there is concern about anaphylaxis. Greer says her home infusion service asks patients who may be at risk of that reaction to receive the first dose in a controlled place, such as an outpatient infusion center or physician's office.

Switching to SCIG includes learning the infusion steps. A clinical guide for high-concentration and facilitated SCIG says the first two to three sessions should take place in the provider's office or with a home infusion nurse. Those sessions allow the care team to confirm that the patient can perform all required steps and tolerates therapy.

For a practice arranging a switch, a concrete step is to book those first two to three supervised sessions as part of the transition plan. The sessions provide time to observe the process before the patient performs the steps independently.

Possible reactions and safety discussions

In a single-center cohort of 42 patients receiving one intravenous immunoglobulin product, 22 patients, or 52%, experienced adverse reactions, and 12, or 29%, switched products. The authors reported no adverse reactions after switching to another IVIG product or to SCIG. These numbers describe that product and cohort.

Greer describes thrombotic events as a boxed warning for IVIG. She links the risk to IVIG's viscosity in the bloodstream and says it matters for people at risk of clot formation. A case report involving a patient with common variable immunodeficiency also stresses vigilance for thrombotic and inflammatory events during IVIG. Its authors describe managing the events by changing the product, infusion rate, and premedication.

Keeping treatment and infection care in view

Immunoglobulin replacement does not prevent every possible complication of antibody deficiency. In an IG Living podcast, Dr. Roger Kobayashi notes that some patients receiving gamma globulin still develop chronic lung disease, inflammatory bowel disease, or cancers.

Allergy & Asthma Network says infections in primary immunodeficiency should be treated promptly and aggressively. The network notes that some infections may need intravenous antibiotics if oral treatment does not work. For patients and practices, that means keeping infection care in the conversation alongside the infusion routine.

This page is general education only. It is not medical advice. Talk with your own doctor about your health.

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