Cost of subcutaneous immunotherapy in a large insured population in the United States.

Allergic rhinitis (AR) affects up to 40% of the United States population, with approximately $11 billion annual medical costs. Allergy immunotherapy is the best option for long-term symptomatic relief, but treatment compliance can be low. The objective was to describe subcutaneous immunotherapy (SCIT)-related costs for patients overall and those with inconsistent treatment. This study observed commercial and Medicare Advantage with Part D health plan enrollees. Included subjects had claims with AR diagnostic codes during 1 January 2011-31 December 2015 and ≥1 SCIT claim during 1 January 2013-31 December 2015 (index date = first SCIT claim date). A control sample was chosen randomly at a 1:3 ratio of SCIT to controls. Inconsistent use was defined as a ≥90 day gap after ≥1 SCIT. Patient characteristics were compared between SCIT patients and controls. Costs were calculated for all SCIT patients and the inconsistent subgroup. Compared with controls (n = 394,479), SCIT (n = 131,493) patients were younger (39.3 vs. 41.4 years), more likely female (56.4% vs. 50.7%) and more likely in a commercial plan (91.6% vs. 83.6%); all p < .001. Among SCIT patients, 15.1% had inconsistent use. Among all SCIT patients, the 3 year total plan-paid SCIT-related costs were $205,741,125 (18% was for inconsistent subgroup) and patient-paid costs were $47,560,450 (15% for inconsistent). Per-member-per-month costs were $0.48 plan-paid and $0.11 patient-paid, with $0.09 plan-paid and $0.02 patient-paid for inconsistent use. This study showed 15% of patients may have costly inconsistent SCIT treatment. Greater understanding is needed regarding the reasons for inconsistent use of subcutaneous allergy immunotherapy.