Cost of Serum Versus Skin Allergy Testing Among Medicare Fee-for-Service Beneficiaries in the United States.

Background: Testing for allergic sensitization can be achieved similarly via skin or serum specific immunoglobulin E (sIgE) testing, although the costs of each method differ. Objective: This study compared cost and utilization of allergy testing utilizing skin vs sIgE testing and whether equal access (parity) to both testing methods affects overall allergy testing costs among Medicare fee-for-service beneficiaries in the United States. Methods: Allergy test utilization and payment data were analyzed using 100% 2019 Medicare fee-for-service claims data. Beneficiaries with any sIgE test, skin prick test, or intradermal skin test associated with ICD-10 codes of allergic rhinitis, asthma, and food allergy were included. Aggregate and per-beneficiary testing cost, number of allergens tested, and number of allergy-related specialist visits incurred were estimated by the testing patterns of sIgE only, skin prick only, intradermal only, skin prick and intradermal, and sIgE plus prick and/or intradermal. Medicare Administrative Contractors (MACs) with parity for all allergy tests and those which restricted sIgE testing were compared. Multivariate linear regression was performed on the association between testing patterns and each cost and utilization measure, controlling for parity, age, sex, race/ethnicity, and dual-eligible status. Results: We analyzed 270 831 patients and 327 263 allergy-related claims. Total payment for all allergy tests was $71 380 866, including $15 903 954 for sIgE tests, $42 223 930 for skin prick tests, and $13 252 982 for intradermal tests. Beneficiaries receiving sIgE tests had only 1.8 fewer allergist visits than those with skin prick tests only (0.8 vs 2.6). Cost of testing per beneficiary was also lower in sIgE testing only compared with skin prick tests only ($161 vs $247). Multivariable regression results showed per-beneficiary payments for allergy testing were on average $22 lower in MACs with parity compared with MACs without parity. Discussion: Serum specific IgE testing is associated with lower costs and fewer allergy specialist visits compared with skin testing. Insurance coverage with parity toward sIgE and skin testing is associated with lower overall costs of allergy testing. Conclusion: Among Medicare fee-for-service beneficiaries in the United States, sIgE testing may be more cost effective compared with skin testing in the management of allergic disease.