Subjects
This is a cross-sectional study that was conducted in adolescent outpatients with asthma who were recruited from a tertiary university hospital. Asthma was diagnosed in accordance with the Global Initiative for Asthma (GINA) guidelines (1). The inclusion criteria were having undergone medical treatment for at least 12 months according to GINA guidelines (1), being between 12 and 18 years old, and having clinically stable disease (no hospitalizations, emergency care visits, or medication changes in the last 30 days). There were no restrictions regarding sex. The exclusion criteria were the presence of any other pulmonary diseases or cardiovascular, neuromuscular, or neurological diseases. The adolescents were divided into two groups: asthma with FAO (FAO group) and asthma without FAO (non-FAO group) groups. The non-FAO group included outpatients under optimal medical treatment in the same hospital who were recruited using the frequency matching method (10) based on sex, age, and body mass index to avoid bias in the comparisons. Adolescents were included in the non-FAO group in small groups of five. Then, every time that five adolescents were included in the FAO group, the subsequent five subjects were included in the non-FAO group until the total sample size was reached.
The Hospital Research Ethics Committee approved the study, and written informed consent was obtained from the adolescents’ caregivers. The costs of transport for all adolescents and their caregivers were covered by the researchers to avoid dropouts. No financial compensation was offered to participate in the study.