[Direct and indirect costs associated with respiratory allergic diseases in Italy. A probabilistic cost of illness study].

BACKGROUND: The respiratory allergies, including allergic rhinitis and allergic asthma, represent a substantial medical and economic burden worldwide. Despite their dimension and huge economic-social burden, no data are available on the costs associated with the management of respiratory allergic diseases in Italy. The objective of this study was to estimate the average annual cost incurred by the National Health Service (NHS), as well as society, due to respiratory allergies and their main co-morbidities in Italy.
METHODS: A probabilistic prevalence-based cost of illness model was developed to estimate an aggregate measure of the economic burden associated with respiratory allergies and their main co-morbidities in terms of direct and indirect costs. A systematic literature review was performed in order to identify both the cost per case (expressed in present value) and the number of affected patients, by applying an incidence-based estimation method. Direct costs were estimated multiplying the hospitalization, drugs and management costs derived by the literature with the Italian epidemiological data. Indirect costs were calculated based on lost productivity according to the human capital approach. Furthermore, a one-way and probabilistic sensitivity analysis with 5,000 Monte Carlo simulations were performed, in order to test the robustness of the results and define the proper 95% Confidence Interval (CI).
RESULTS: Overall, the total economic burden associated with respiratory allergies and their main co-morbidities was € 7.33 billion (95% CI: € 5.99-€ 8.82). A percentage of 27.5% was associated with indirect costs (€ 2.02; 95% CI: € 1.72-€ 2.34 billion) and 72.5% with direct costs (€ 5.32; 95% CI: € 4.04-€ 6.77 billion). In allergic asthma, allergic rhinitis, combined allergic rhinitis and asthma, turbinate hypertrophy and allergic conjunctivitis, the model estimate an average annual economic burden of € 1,35 (95% CI: € 1,14-€ 1,58) billion, € 1,72 (95% CI: € 1,14-€ 2,43) billion, € 1,62 billion (€ 0,91-€ 2,53) billion, € 0,12 (€ 0,07-€ 0,17) billion, € 0,46 (€ 0,16-€ 0,92) billion respectively.
CONCLUSIONS: To our knowledge, this is the first study in which direct costs (incurred by NHS) and indirect ones (incurred by the society) were taken into account to estimate the overall burden associated with respiratory allergies and their main co-morbidities in our Country. In conclusion, this work may be considered an efficient tool for public decision-makers to correctly understand the economic aspects involved by the management and treatment of respiratory allergies-induced diseases in Italy.