The economic cost of neutrophilic asthma in adult patients from the Italian general population.

<bold>Aim:</bold> Neutrophilic asthma is a phenotype of asthma with frequent symptoms and hospital admissions. The present study aims to provide a real-life assessment of the economic cost of neutrophilic asthma in patients from the general adult population in Italy. <bold>Methods:</bold> A prevalence-based cost-of-illness study was conducted on adult subjects with current asthma and low blood neutrophils (<5000 cells/mm^-3; n = 168, mean age 43.1 years, female 46.4%) or high blood neutrophils (≥5000 cells/mm⁻³; n = 56, mean age 41.6 years, female 50.0%). These patients were identified in the Gene Environment Interactions in Respiratory Diseases (2008-2010) survey in Verona, Italy. The costs attributable to poor control of asthma (emergency department visits, hospital admissions, loss of productivity and leisure time) were calculated from the societal perspective following the bottom-up approach based on 2013 rates, wages, and prices (obtained from official Italian sources). The mean annual cost per patient [and 95% confidence interval (95%CI)] was estimated separately by neutrophil level using a two-part model (first part: logistic regression; second part: gamma regression) with robust standard errors. <bold>Results:</bold> The mean annual cost attributable to poor control of asthma was 156 (95%CI: 86-225) and 400 (95%CI: 82-719) euro per patient with low or high blood neutrophils, respectively. Conditional on reporting any cost, these costs were estimated to be 1,005 (95%CI: 735-1,275) and 2,241 (95%CI: 981-3,501) euro, respectively. <bold>Conclusion:</bold> In the general population the economic cost of asthma is high and increases significantly with the level of blood neutrophils.