Risk factors for fixed airflow obstruction in children and adolescents with asthma: 4‐Year follow‐up

Abstract Background Asthma is a disease with reversible bronchoconstriction; however, some patients develop fixed airflow obstruction (FAO). Previous studies have reported the incidence and risk factors of FAO in adults; however, the corresponding factors in children remain poorly understood. Aim To evaluate the incidence and risk factors of FAO in children and adolescents with asthma. Method Observational and prospective cohort study with a 4‐year follow‐up of clinically stable patients with asthma (from 6‐8 years old). Anthropometric data, history of asthma, number of hospitalizations, frequent exacerbations, asthma severity, asthma control, inhaled corticosteroid dose, atopy, and lung function were analyzed as potential risk factors for FAO. FAO was defined by a ratio of the forced expiratory volume in the first second to the forced vital capacity below the lower limit of normal, even after inhaled and oral corticosteroid treatment. Results Four hundred and twenty‐eight patients were recruited, and 358 were analyzed. The FAO incidence in children and adolescents with asthma was 9.5% (n = 34), starting at 10 years of age. Age, body mass index, hospitalizations for asthma, bronchodilator response, frequent exacerbations, length of exacerbations, and asthma severity were associated with FAO. Frequent exacerbations (odds ratio [OR] = 4.0; 95% confidence interval [CI] = 1.3‐11.7) and asthma severity categorized as steps 4 to 5 (OR = 3.5; 95% CI = 1.6‐7.6) remained risk factors. Conclusions Frequent exacerbations and asthma severity are the risk factors for FAO in children and adolescents with asthma.