We should continually improve tools for evaluating asthma. The aim of this study was to evaluate whether the FEV₁/FVC ratio in the lower range of normality is associated with worse outcomes in asthmatics without airway obstruction.

We screened asthmatics at eight clinics. Subjects answered the Asthma Control Questionnaire and underwent spirometry. We assigned individuals without airway obstruction in three groups according to the post bronchodilator FEV₁/FVC ratio: lower range of normality, intermediary range of normality and upper range of normality. Asthma outcomes were hospital admission due to asthma during the preceding year, non-controlled asthma symptoms and moderate-high inhaled maintenance therapy need.

In subjects from six to 18 years old, the rate of hospital admission was higher in the group with FEV₁/FVC ratio in the lower range of normality as compared with the other two groups but the frequency of non-controlled symptoms of asthma and moderate-high dose of inhaled maintenance therapy need was similar. From 19 to 59 years old, the rate of moderate-high inhaled maintenance therapy need was higher in the group with FEV₁/FVC ratio in the lower range of normality as compared with the other two groups, but the frequency of hospital admissions and non-controlled symptoms of asthma was similar. Above 59 years old, there was no difference in clinical asthma outcomes between lung function groups.

FEV₁/FVC ratio in the lower range of normality is a marker of worse clinical outcomes in asthmatics without airway obstruction.