Shadow cost of oral corticosteroids-related adverse events: A pharmacoeconomic evaluation applied to real-life data from the Severe Asthma Network in Italy (SANI) registry

Background: Asthma is one of the most common non-communicable respiratory diseases, affecting about 6% of the general population. Severe asthma, even if afflicts a minority of asthmatics, drives the majority of costs of the disease. The aim of this study is to create a pharmacoeconomic model to predict the costs of corticosteroid-related adverse events in severe asthmatics and applying it to the first published epidemiologic data from the Severe Asthma Network in Italy (SANI) registry. Methods: The analysis was conducted from the perspective of the Italian National Healthcare System (INHS). Model inputs, derived from literature, included: asthma epidemiology data, frequency of adverse events, percentage of severe asthma treated with OCS and adverse event cost (Diagnosis-Related Group (DRG) national tariffs). We estimated costs per different patient groups: non-asthma controls, mild/moderate and severe asthmatics. Final results report estimated direct cost per patient and total direct cost for overall target population, showing economic impact related to corticosteroid complication. Results: Based on epidemiological data input, in Italy, asthmatic subjects resulted about 3,999,600, of which 199,980 with severe asthma. The number of patients with severe asthma OCS-treated was estimated at 123,988. Compared to the non-asthma control cohort and to that with moderate asthma annual cost per severe asthmatic patient resulted respectively about €892 and €606 higher, showing a corticosteroids shadow cost ranging from 45% to 30%. Applying the cost per patient to the target population identified for Italy, the budget impact model estimated a total annual cost related to OCS-related adverse events of €242.7 million for severe asthmatics. In respect with non-asthmatic and moderate population, an incremental expenditure of about € 110.6 million and €75.2, respectively, were shown. Conclusions: Our study provides the first estimates of additional healthcare costs related to corticosteroid induced adverse events in severe asthma patient. Budget impact model results highlighted the relevant economic impact of OCS-related adverse events in severe asthma patients. The future extrapolation of additional data from SANI registry will support the development of a model to investigate the role of corticosteroids sparing drugs.