Data on the epidemiology of asthma in Portugal were mainly grounded in studies using questionnaires and covering limited age groups. Studies assessing the prevalence of asthma diagnosis and of its sub-groups with more accurate methods are therefore needed This study aims to determine the prevalence of asthma, difficult-to-treat and severe asthma in Portugal, and to characterize patients to better understand their disease characteristics, treatment profile and health care resource use to improve clinical management of the disease.
We will conduct a population-based nationwide study with a multicentre stepwise approach, enrolling 7500 adult subjects, randomly selected, from the Portuguese National Health Service patients' database of 38 primary care centres:
STAGE 0 - Phone call invitation and enrolment of participants STAGE 1 - Telephone interview survey to assess respiratory symptoms. STAGE 2 - Clinical assessment, diagnostic confirmation, and patient characterization STAGE 3 - Characterization of asthma patients (sub-group) and characterization of difficult- to-treat asthma \& severe asthma patients after 3 months follow up period.
