Economic impact of infections among patients with primary immunodeficiency disease receiving IVIG therapy.

Purpose: There are limited data on the cost of infections among patients with primary immunodeficiency disease (PIDD) in clinical practice. The purpose of this study was to assess the economic impact, from the US commercial payer perspective, of infections in a cohort of patients with PIDD who were administered intravenous immunoglobulin (IVIG) therapy.

Methods: This study used administrative claims from the MarketScan(®) Database. Patients with a PIDD diagnosis, one or more prescription(s) for IVIG therapy between January 1, 2008 and February 28, 2010, and one or more prescription(s) for IVIG at least 3 months following first IVIG prescription, were selected. The study period consisted of a 7-month window following first IVIG prescription. Study measures included infection-related medical resource use and expenditures. Adjusted infection-related hospitalization expenditures were estimated using a generalized linear model, controlling for demographics, comorbidities, and infection type.

Results: A total 1,742 patients with PIDD and consistent IVIG use were identified, with 490 patients (mean age 43; 58.8% female) having one or more infection(s) during the 7-month study period. Infection-related inpatient hospitalizations were the most expensive component of care (US$38,574 per hospitalized patient). In multivariate modeling, the presence of a blood infection during the hospitalization (versus [vs] no blood infection), having diabetes, and younger age (<18 vs 55-64) were associated with significant increases in infection-related hospitalization expenditures (49.3%, 55.3%, and 76.5%, respectively) (P<0.05).

Conclusion: Health care expenditures for infections in PIDD patients receiving IVIG therapy can be substantial, particularly for inpatient care. Future evaluations assessing the incremental cost of optimizing IVIG therapy should include evaluation of the effects on infection-related medical expenditures.