Background: Patients with immune-mediated diseases such as rheumatoid arthritis, psoriatic arthritis, or inflammatory bowel disease (IBD) are increasingly being prescribed biologics. While biologics may account for roughly 2% of total prescriptions in the United States, they account for over 35% of net drug spending and for over 80% of the growth in net drug spending.1,2 Severe hypersensitivity reactions may occur in up to 10% of patients after the administration of biologic infusions, more commonly after the first infusion but sometimes after multiple infusions.3,4 Severe hypersensitivity reactions such as cardiovascular or respiratory compromise or anaphylaxis require prompt medical attention and trained professionals. Despite this several insurance companies frequently require patients with immune-mediated diseases to receive their biologic infusions at home instead of a facility, primarily due to the decreased costs associated with infusions at home.5 In this study, we compare the outcomes of patients receiving intravenous biologic infusions at home (“home infusers”) versus at a facility (“facility infusers”) using Optum, a large insurance claims database.

Methods: We performed a retrospective cohort analysis of patients with immune-mediated diseases who received biologic infusions between 2007 and 2017 using the Optum Clinformatics™ Data Mart. The Optum database contains de-identified patient-level information on roughly 18 million privately insured patients per year. Our primary outcomes were hospitalization within one day of infusion and emergency room (ER) visit within one day of biologic infusion. Reason for hospitalization or ER visit was not known. Our secondary outcome was all-cause mortality within 30 days of biologic infusion. We conducted multivariate analysis adjusting for age, gender, Charlson comorbidity score, year of infusion, and presence of IBD at the time of infusion for our outcomes.

Results: 47,784 patients with immune-mediated diseases received biologic infusions between 2007 and 2017, of which 6.0% (n=2871) were home infusers (Figure). For facility infusers, 70.9% had rheumatic disease and 27.7% had IBD. For home infusers, the opposite was true, with 68.4% having IBD and 27.1% having rheumatic disease. Compared to facility infusers, home infusers were more likely to be younger (mean age 42.8 years versus 52.0 years), male (44.5% versus 32.3%), and have a Charlson comorbidity score of zero (63.1% versus 31.1%). In the multivariate analysis, home infusers were more likely to be hospitalized within one day of infusion (OR 1.35 [95% CI, 1.13-1.62], p = 0.001) and have an ER visit within one day of infusion (OR 1.37 [95% CI, 1.03-1.83], p = 0.03). There was no significant difference in 30-day mortality between home infusers (n=4) and facility infusers (n=169).

Conclusions: This study demonstrates that an increasing number of patients with immune-mediated diseases receive biologic infusions at home, subjecting them to an increased risk of adverse clinical outcomes. While home infusions may be cost-effective for insurance companies and convenient for patients, they may have higher rates of hospitalization and ER visits within one day of the biologic infusion.

IMAGE 1: Trend of home infusions in our database