Background: Severe persistent asthma is often poorly controlled and its prevalence in pneumology and allergy hospital units in Spain is unknown.

Objectives: To determine the prevalence of uncontrolled severe persistent asthma in hospital units in Spain and to describe the clinical characteristics of this condition.

Methods: An observational, cross-sectional study was conducted in 164 Spanish hospital pneumology and allergology units. A record was made of all patients with asthma and patients with uncontrolled severe asthma (diagnosed on the basis of clinical criteria) seen in these units over 6 months. Information on sociodemographic variables, clinical characteristics, pharmacological asthma treatment, skin prick testing, total serum
immunoglobulin E (IgE) levels, pulmonary function (forced expiratory volume in the fi rst second and forced vital capacity), asthma control (Asthma Control Questionnaire [ACQ]), and quality of life (Asthma Quality of Life Questionnaire) was collected.

Results: According to the clinicians’ judgement, 1423 out of 36 649 asthma patients (3.9%, 95% confidence interval, 3.7%-4.1%]) had uncontrolled severe persistent asthma. These patients had a mean (SD) ACQ score of 3.8 (1.0); 55.8% had a positive skin prick test to common aeroallergens and 54.2% had high levels of total serum IgE. The agreement between the assessment of asthma control based on clinicians’ criteria and according to the Global Initiative for Asthma (GINA) guidelines was moderate (63.2%, κ=0.337), with an underestimation of asthma severity by clinicians; 53.2%
of the patients classified as having controlled moderate to severe asthma had uncontrolled severe persistent asthma according to GINA criteria.

Conclusions: There is a low prevalence of uncontrolled severe persistent asthma in patients seen at hospital units in Spain according to clinical
criteria, although it should be noted that level of asthma control is overestimated by clinicians.

Key words: Prevalence. Asthma. Uncontrolled. GINA guidelines.