Background: Previous estimates of the national economic burden of allergic rhinoconjunctivitis (AR/AC) have relied on data analyses in which AR/AC was the primary International Classification of Diseases-ninth revision-Clinical Modification (ICD-9-CM)-coded diagnosis. These studies ignore the costs when AR/AC was a secondary diagnosis to other disorders such as asthma and sinusitis.
Objective: We sought to determine the national direct cost of illness for AR/AC.
Methods: An expert panel used the Delphi technique to estimate the proportion of visits coded by other primary ICD-9-CM diagnoses in which AR/AC was a significant secondary comorbid condition. The costs of this proportion were deemed to be "attributable" to AR/AC and were added to the costs when allergic rhinitis and allergic conjunctivitis were the primary diagnoses.
Results: The cost when AR/AC was the primary diagnosis was $1.9 billion (in 1996 dollars). The cost when AR/AC was a secondary diagnosis was estimated at $4.0 billion, giving an estimate of $5.9 billion for the overall direct medical expenditures attributable to AR/AC. Outpatient services (63%, $3.7 billion), medications (25%, $1.5 billion), and inpatient services (12%, $0.7 billion) accounted for the expenditures. Children 12 years and younger accounted for $2.3 billion (38.0%).
Conclusion: Upper airway allergy is an expensive disease process because of its readily apparent manifestations as AR/AC and its contribution to other airway disorders.