A Longitudinal Study of a Selected Pediatric Asthmatic Population with Normal and Abnormal Spirometry at Baseline: An Emphasis on Treatment Outcomes

Abstract

Purpose

It is still unclear whether considering abnormal spirometry as a marker for disease control can help physicians adjust asthma controllers in children because of the scarcity of pediatric studies. We aimed to investigate the prevalence of abnormal spirometry in a selected pediatric asthmatic population and its effect on longitudinal outcomes.

Patients and Methods

This retrospective cohort study was conducted at the Songklanagarind Hospital, Thailand. Children with asthma aged <18 years were recruited for review if they attended the clinic and underwent acceptable spirometry with bronchodilator responsiveness (BDR) tests after receiving asthma treatment for at least 3 months between January 2011 and June 2022. Differences in baseline characteristics, atopic factors, asthma treatment, and outcomes were analyzed between the normal and abnormal spirometry groups over a 12-month post-spirometry period.

Results

The mean age of the 203 enrolled patients was 10.9 ± 2.6 years. Abnormal spirometry, defined as airflow limitation or the presence of BDR, was observed in 58.1% of patients. No significant differences were observed in baseline characteristics, atopic factors, asthma treatment, or outcomes between the normal and abnormal spirometry groups. Further analysis of 107 patients with abnormal spirometry with symptom control revealed that physicians adjusted the asthma controller based on spirometry and symptoms in 84 and 23 patients, respectively. There was no significant difference in the loss of disease control over the 12-month post-spirometry period between the two groups.

Conclusion

Abnormal spirometry was found in 58.1% of treated school-aged patients with asthma. Abnormal spirometry results were not associated with poor asthma outcomes during the 12-month follow-up. Both symptom-based and spirometry-based adjustments of asthma controllers resulted in comparable symptom control over a 12-month follow-up period in the selected population.

Keywords:

• pulmonary function test
• lung function test
• childhood asthma
• bronchodilator responsiveness

Abbreviations

BDR, bronchodilator responsiveness; FEV1, forced expiratory volume in 1 second; FEV1/FVC, ratio of FEV1 to forced vital capacity; FEF25–75%, forced expiratory flow between 25% and 75% of vital capacity; FeNO, fractional exhaled nitric oxide; GINA, Global Initiative for Asthma; ICS, inhaled corticosteroids; IQR, interquartile range; SD, standard deviation; PEFR, peak expiratory flow rate.

Data Sharing Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Ethics Approval and Informed Consent

Ethics committee approval from the Faculty of Medicine, Prince of Songkla University (REC-65-261-1-1, approved on August 15, 2022) was obtained prior to study initiation. The study was performed in accordance with the Declaration of Helsinki and informed consent was obtained from the parents or legal guardians of all study participants prior to study commencement.

Acknowledgments

We would like to thank all the respiratory nurses of the Pediatric Pulmonology and Allergy Clinic at Songklanagarind Hospital, who performed standard spirometry for all patients with asthma throughout the study period, as well as detailed interviews for asthma symptom control assessment of all patient visits.

Author Contributions

All authors made a significant contribution to the work reported, whether that was in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest related to this work.

Additional information

Funding

This work was supported by the Faculty of Medicine, Prince of Songkla University (grant number REC 65-261-1-1). The sponsor had no involvement in the study design, analysis and interpretation of data, or in the decision to submit the article for publication.