Prevalence of Asthma According to Disease Severity in Portugal: Preliminary Findings from the EPI-ASTHMA Study

In Portugal data on the epidemiology of asthma is mainly grounded in questionnaire studies. Studies assessing the prevalence of asthma and its subgroups using accurate methods are needed. The study aimed to determine the prevalence of asthma, difficult to treat and severe asthma in Portugal in adults. An observational study was implemented in 38 primary care centres of the National Health Service and data is being processed. A stepwise approach was followed: Stage 0- phone call invitation to randomly selected adults; Stage 1- phone interview assessing respiratory symptoms; Stage 2-clinical assessment with physical examination, diagnostic tests, and patient-reported outcome measures, to confirm the diagnosis of those with possible asthma at stage 1; Stage 3-evaluation of patients with asthma after 3 months based on electronic health record (EHR) review and a phone interview. The prevalence of asthma was calculated in relation to the study population. Disease severity was based on GINA treatment steps (based on current/recommended start treatment). A total of 7556 (51[40-64] y; 43% male) invited adults accepted to participate (stage 1). At stage 2, 1857(25%; 54[43-66] y; 40% male) were assessed and 518(28%; 52[41-65]y; 38% male) were diagnosed with asthma. More than half (n=353; 68%) had their disease uncontrolled (Control of Allergic Rhinitis and Asthma Test≤24). Regarding healthcare use, 152 (29%) had ≥2 exacerbations, 83 (16%) ≥1 emergency department visit and 13 (2.5%) one hospitalization in the past year. A total of 160 (31%) were at GINA Step 1-2, 211 (41%) in GINA step 3 and 147 (28%) in GINA step 4-5. Approximately 7% (6.3 – 8.0) of participants had asthma (0.8% ACO). Stage 3 was completed by 457 patients (88%), 305(66%) had asthma registered in their EHR. The preliminary frequency of asthma and its sub-sub-groups in Portugal is aligned with international data. EPI-ASTHMA will provide comprehensive data to better understand asthma prevalence and patients’ characteristics in Portugal. Keywords: Asthma, Prevalence, Epidemiology, severe asthma, difficult-to-treat asthma