The Efficacy and Cost Effectiveness of Subcutaneous Immunoglobulin (SCIG) Replacement in Patients with Immune Deficiency Secondary to Chronic Lymphocytic Leukemia

Introduction:

The most common immune defect in chronic lymphocytic leukemia (CLL) is hypogammaglobulinemia, secondary to the underlying malignancy and intensified by chemotherapy. Subcutaneous immunoglobulin (SCIG) infusions have been widely adopted to treat patients with primary immune-deficiency (PID) this approach has not been widely accepted in CLL. The goal of this program was to evaluate SCIG in patients with CLL to determine: a) whether it is possible for the CLL population to manage SCIG; b) whether SCIG is effective in these patients; c) whether using SCIG improves patient quality of life, and d) whether using SCIG produces a cost-saving when compared to IVIG.

Methods:

We implemented a nurse-led SCIG clinic within the CLL Clinic at CancerCare Manitoba for ambulatory CLL patients with hypogammaglobulinemia experiencing infectious complications (documented IgG <4g/L and > 2 courses of oral antibiotics in a 12 month period, or 1 severe infection IV antibiotics). Patients were screened for eligibility, trained, and transitioned (85% enrollment rate). Patients started replacement therapy at a dose of 12 grams/month with dose

escalation based on infections rather than trough IgG levels. Demographic and clinical characteristics were collected, in addition to pre- and post-antibiotic use, treatment satisfaction and quality of life measurements along with cost analysis.

Results:

In its first 2 years, 53 patients with CLL were referred to the program [n=45(85%) enrolled, n=4(7.5%) ineligible (mean age 71 years), and n=4(7.5%) declined (mean age 77 years)]. Reasons for declining were related to the presence of anxiety and a fear of needles. Only 2 patients (4%) switched back to IVIG within 3 months of starting SCIG but both patients lived outside the city limits and did not have the ability to do repeat training and support with the SCIG nurse.

Median duration of participation on program is 16 mos. (range 1-24 mos), male gender 27(60%), median age 69 years (range 48-91), rural dwelling 17(38%), 36 patients (80%) were married with a partner to assist. Median time since CLL diagnosis was 8 years (range 1-26 years). Most (84%) of patients had received prior treatment for CLL & 43% were on chemotherapy concurrent with SCIG.

Trough IgG Levels: At Diagnosis: Median IgG 5.5g/L , 65% hypogammaglobulinemia

Lowest charted IgG: 2.84g/L

Enrolled patients comprised 60% n=27 of the sample with 40% n=18 transitioned from IVIG infusions.

Of the subset of patients (n=27) that had no prior IgG replacement:

IgG (dx) 3,02; lowest IgG 3.34; 1 month post 4,24; 3months post 5.29; 6 months post 5.79g/L showing a steady rise in levels.

Using a low dose approach, our median SCIG dose was 12 grams/month vs. weight-based dosing. (200-400mg/kg, mean weight 81 kg, mean dose 24 grams/infusion). This represented a 50% savings per infusion of donor IgG.

Resource Savings: (n=45 patients) In the first 24 months: a total of 597 IVIG infusions were saved, which represents 1791 infusion chair hours. The savings in each subsequent 12 month period is projected to be 540 hours, and 1620 infusion chair hours. SCIG infusions represent an additional 50% savings in supply costs.

Donor IgG Savings: (n=45)

By not using dosing based on patient weight, our low dose approach reduced infusion doses by 50%. In the first 24 months, the 597 infusions saved 7164 grams of product (equivalent to $358, 200 Canadian funds).

Savings in each subsequent 12 month period would be an additional 6480 grams (equivalent to $324,000 Canadian funds).

Antibiotics Use:

The median number prescriptions/patient decreased 3 fold after the initiation of SCIG. (109 Prescription pre vs. 46 Prescription post SCIG).

Treatment Satisfaction & Quality of life data will be presented with patients reporting significant improvements citing multiple benefits. Overall, patients were very satisfied with <4% switchback rate. At 6 months, 94% are satisfied, somewhat or extremely satisfied with SCIG's ability to prevent infections. 29 patients (81%) reported no side effects, 31(86%) report SCIG being easy to infuse and 60% patients extremely satisfied and 40% satisfied or somewhat satisfied.

Conclusions:

The implementation SCIG at our cancer center has changed our standard of care for Ig replacement and has resulted in significant cost saving, efficacy and improved quality of life and treatment satisfaction.