Background: The last decade has seen new classifications of the pathophysiology of asthma that have changed the treatment options available.
Objectives: To update data on the prevalence of T2 asthma, comorbidities, biomarker characterization, and costs of severe asthma in patients aged ≥12 years, taking into account new classifications and treatment options.
Methods: Retrospective, observational, nationwide study using a top-down approach. Data were obtained from BIG-PAC^®, an electronic medical record database of 1.7 million patients in Spain. The study population comprised patients aged ≥12 years who had received medical care during the period 2016-2017 and been diagnosed with asthma at least 1 year prior to the index date. Patients were followed for 1 year. 
Results: The prevalence of asthma was 5.5%. Asthma was severe in 3031 of these patients (7.7%), 81.2% of whom presented T2 asthma. Among patients with severe asthma, 64.1% had uncontrolled disease, 31.2% were oral corticosteroid–dependent (37% in the uncontrolled severe asthma group), and only 3.8% were receiving biologics. The most common T2 comorbidities were allergic rhinitis (66.1%), atopic dermatitis (29.1%), and chronic rhinosinusitis with nasal polyps (14.6%). Mortality rates in the total population and uncontrolled severe asthma groups were 4.2% and 5.5%, respectively. The total annual costs per patient with severe asthma were €5890 (uncontrolled) and €2841 (controlled). 
Conclusions: In the era of biologics, most severe asthma patients present T2 asthma. Despite the availability of new treatments, rates of oral corticosteroid–dependent patients with uncontrolled severe asthma remain high, although biologics continue to be underused. The costs of uncontrolled severe asthma are twice as high as those of controlled severe asthma.

Key words: Asthma prevalence, Severe asthma, Type 2 asthma, Uncontrolled asthma, Asthma comorbidities, Asthma costs