IgG Therapy for the Home-Based Patient: Administration and ... - NHIA

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able to perform their own infusions, at home when it’s convenient, without having to travel to and from a treatment center. A 2010 study showed that patients preferred SCIG over IVIG therapy (92%) and home therapy over therapy at the clinic/physician (83%). 12 Unfortunately, patients requiring higher IgG doses, such as those with autoimmune diseases, may not be appropriate candidates for SCIG therapy due to the large volume of fluid that would need to be delivered. This is especially true for patients on formulations with comparatively lowerconcentration IgG (i.e. 10% vs 16% or 20%). Similarly, patients who are very lean may not be suitable candidates for SCIG because they often have limited appropriate sites for SC access. For SCIG to be successful, patients and caregivers must be committed to learning and adapting to selfcare. They should also have a demonstrated history of therapy compliance. Independence is typically achieved after two to four nurse teaching visits with continued clinical monitoring and patient followup. Dosing and Conversion to SCIG Several studies demonstrate favorable improvement in infection rates, hospital admissions, and overall morbidity for patients on SCIG. 7,1316 But, how much IgG is needed to achieve these results, and what is the best dosing strategy for patients just starting SCIG therapy and/or converting from IVIG? Not all patients respond the same way to the many IgG formulations on the market. Differences in pH, osmolarity, amount of sucrose, and amount of IgA, make product selection very individualized. Similarly, there is no cookie cutter formula for dosing—although higher doses are beginning to be supported in the literature as offering improved clinical benefits and quality of life for patients. 17 Unlike IVIG, SCIG doesn’t immediately enter the circulatory system during administration. For this reason, it has a lower systemic bioavailability and more stable serum levels following administration. Weekly administration of SCIG leads to stable steadystate serum IgG levels with lower peak levels and higher trough levels compared to monthly IVIG treatment (see Exhibit 2). The FDA recognized this difference and adjusted dosing to achieve a similar “area under the curve” (AUC) by using a productspecific multiplier for calculating dosages. Formulas for converting IVIG doses are provided in package inserts and available from IgG manufacturers online (see Exhibit 3). The optimal dose of IgG for primary immune deficiency was considered to be 400800 mg/kg/month (100200 mg/kg/week for SCIG) with the goal of achieving serum levels of 500 mg/dL or greater. 18,19 But, in 2006, the PID Committee of the AAAAI issued a report in which it asserted that the dose of IgG should be titrated to achieve a trough level greater than 500 mg/dL in agammaglobulinemic patients and that trough levels greater than 800 mg/dL have the potential to improve pulmonary outcomes. 3 This was further demonstrated in a 2010 metaanalysis of PIDD patients on IVIG therapy and experiencing pneumonia, whose rates of infection were reduced by increasing the IgG trough levels to midnormal range (1,000 mg/dL). 17 A subsequent study, published in 2012, examined a broader set of outcomes and also favored higher doses of IgG. Researchers comparing results from two parallel clinical studies found that PIDD patients who maintained a higher mean IgG dose (1.5 times higher) had significantly lower rates of nonserious infections, hospitalization, antibiotic use, and missed work/school activity. In addition, the higherdose group experienced lower health care utiliza Exhibit 2 Subcutaneous Versus Intravenous Serum Ig levels Total IgG 1600 1400 1200 1000 800 600 400 Intravenous Ig Subcutanenous Ig 0 2 4 6 8 10 12 14 16 18 20 22 Days Source: P&T Product Profiler – Hizentra Vol. 35, Issue 8 / August 2010 Section 2 / adapted from Berger 2004. Available at http://www.ptcommunity.com/ptjournal/fulltext/Profiler_Hizentra/Profiler_Hizentra.pdf Exhibit 3 FDA-Recommended Dose Conversion for SCIG • 20% products = IVIG dose (g) x 1.53 / number of weeks between doses • 10% products = IVIG dose (g) x 1.37 / number of weeks between doses 4 IgG Therapy for the HomeBased Patient: Administration and Delivery Method Considerations
tion and improved indices of wellbeing compared to the group treated with traditional IgG doses. 18 Many clinicians now believe that the mean dose adjustment coefficient and the mean trough level ratio should only be used as rough guides in dosing. As additional outcomes, such as slowing of disease progression, frequency of infection, days of work/school missed, etc., are considered, experienced clinicians are tending toward higher doses while relying on patient monitoring to adjust therapeutic levels of IgG. In a survey of immunologists, those with more indepth experience—more than 10% of their practice was devoted to PID patients—were significantly more likely to target higher serum levels (above 750 mg/dL); whereas those with fewer than 10% PID patients usually targeted lower serum levels (500750 mg/dL). 20 Home infusion and specialty pharmacy providers can play a critical role in patient monitoring by collecting supporting documentation on the therapeutic effectiveness of IgG regimens from a variety of perspectives, including: response to therapy, abatement of symptoms, and quality of life. This data provides meaningful feedback for physicians working to find each patient’s dosing “sweet spot,” and also aids in building a case for reimbursement, especially if the patient’s recommended dosage falls outside the “normal” payer guidelines. SCIG Administration SCIG administration presents some unique challenges from a clinical perspective. With the medication itself, volume and viscosity are key factors in care planning. The therapy also involves a different—but similar—set of supplies than those used to administer IVIG. For example, the home infusion/specialty pharmacy care team should map out a regimen based on the prescribed dosing parameters. They need to consider the individual patient and total volume of therapy to determine the number of fractionations and sites to be infused with each administration. As a rule of thumb, infusions should last 4550 minutes, and should not be longer than 90 minutes. Generally, no more than 15 mL should be administered in any one site. In order to limit swelling, a rate of 20 mL/hour is suggested for rapid infusions; 4 mL/hour is suggested for longer infusions. 11 SCIG is viscous—much more so than the sterile water used to calibrate typical IV administration rates—so tubing sets need to be adjusted to achieve the desired rate. For example, pumps and tubing may need to be set at 600 mL/hr to deliver 20 mL/hr to the patient. There are several infusion pumps and needles specifically designed for SC administration— some pumps use only proprietary sets. Many pump manufacturers offer sample supply lists online to prompt pharmacy IgG Therapy for the HomeBased Patient: Administration and Delivery Method Considerations 5
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Page 3 and 4: Author Bios: Hetty Lima, R.Ph., FAS
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IgG Therapy for the Home-Based Patient: Administration and ... - NHIA

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