Factors associated with the control of severe asthma.

INTRODUCTION: Control is a priority treatment objective in asthma, and classification based on control is recommended in the follow-up of asthmatic patients. Different factors affect this control, and there are several regional differences, both in terms of prevalence and in terms of management and degree of control.

OBJECTIVE: To evaluate the factors associated with control of severe asthma in routine clinical practice.

MATERIAL AND METHODS: This was a prospective, cross-sectional, observational study of patients with severe asthma who were receiving treatment with a fixed combination of a corticosteroid (at least 800 microg/day of budesonide or equivalent) and an inhaled beta(2)-adrenergic agonist in respiratory medicine and allergology clinics throughout Spain. The authors collected demographic and socioeconomic data, as well as clinical data on asthma. The patients also completed a self-administered validated questionnaire-the Asthma Control Questionnaire (ACQ)-about the control of their asthma.

RESULTS: The authors included 1471 patients, of whom 1224 (83%) were valid for the final analysis. Women accounted for 61%. Mean age was 51 +/- 16 years. The mean number of exacerbations during the previous year was 2.0 +/- 2.0. The global score on the ACQ was 1.8 +/- 1.1 (0 = no symptoms; 6 = maximum number of symptoms). Only 20.4% of patients were well controlled (ACQ < 0.75), and 55.7% of patients were poorly controlled (ACQ > 1.5). The multivariate analysis revealed that the variable with the greatest effect on control of asthma was the number of exacerbations during the previous year: when the number of exacerbations increased from 0 to 1 or more, the ACQ score increased by 0.56 points. Employed patients had a mean of 0.23 points less (better control) than unemployed and retired patients. Control of asthma was also significantly affected by adherence to treatment, patient knowledge of the disease, body mass index, gender, and number of visits to a physician in the previous 3 months.

CONCLUSIONS: Many patients with severe asthma have poor control of their disease. The number of exacerbations is the variable with the greatest effect on control of asthma. Knowledge of the disease and adherence to treatment are associated with better control.