Patients with uncontrolled asthma or severe asthma are at increased risk of severe asthma exacerbation. Severe asthma exacerbation is associated with considerable morbidity and premature death. There are few real life data on the incidence of severe asthma exacerbation; and data on asthma-related mortality, because of low numbers, is even more rare. With this study, using data from six European large electronic health care databases, we want to i) study the rate of severe asthma exacerbations (both in asthma and severe asthma patients), ii) study the mortality rate in patients with severe asthma and iii) study the asthma-related mortality rates associated with an asthma exacerbation in patients with severe asthma. A retrospective cohort study will be conducted including patients aged 5 years or older and diagnosed with asthma, using multi-national, multi-databases from six European electronic health care databases from the Netherlands, Italy, United Kingdom (UK), Denmark and Spain. The study period runs from 2008 until 2013. The study population will consist of all patients, 5 years or older, present in the respective databases for at least 1 year, and diagnosed with asthma. The primary endpoints consist of severe asthma exacerbation and death. Severe asthma exacerbation is defined as need of systemic corticosteroids, OR hospital visit (ER or admission), all for reasons of asthma exacerbation. Death will be assessed either from the demography table or based on death specific disease codes. Where available, cause of death will be evaluated and classified as ?asthma? or? non-asthma? related. Data from six electronic health care databases from Europe will be used, namely the Integrated Primary Care Information Project (IPCI) from the Netherlands, the Sistema d’Informació per al Desenvolupament de la Investigació en Atenció Primària (SIDIAP) from Spain, Clinical Practice Research Datalink (CPRD) from the UK, Aarhus (Denmark), and the Health Search CSD Longitudinal Patient Database (HSD) and Pedianet database, both from Italy. Descriptive statistics will be used. Categorical data will be presented as counts (n) and proportions (%) along with (95% confidence intervals). For continuous data, the number of observations (n), mean, standard deviation, median (with interquartile range) will be presented. The incidence rate of severe asthma exacerbation will be calculated by dividing the numerator (number of severe asthma exacerbations) by the total number of years of follow-up. Differences in incidence rate (by gender, age, country, calendar year) will be tested using Poisson Regression. Asthma-related mortality will be assessed in a predefined time window (15, 30, 45 – 60 days) upon severe asthma exacerbation. In addition, a pooled analysis will be conducted, pooling the data from the different databases. The first report will provide details on the incidence rate of severe asthma exacerbations in patients with asthma and in patients with severe asthma. This first report will also provide the number of patients who died during follow-up. The second report (if number of patients who died is high enough) will provide asthma-related mortality rates.