Methods
This study was exempt from IRB review by the New York Medical College Institutional Review Board under federal guidelines 45CFR46.104, section 4ii, as the data was de-identified, and the investigators did not contact or re-identify the subjects. A retrospective data extraction of all children with a diagnosis of asthma who underwent complete pulmonary function tests (PFTs) over a 5-year period (January 2014 to January 2019) from the Pediatric Pulmonary Function Laboratory at Maria Fareri Children’s Hospital at Westchester Medical Center was performed, and subsequently, a review of individual clinical records was conducted. Patients were selected if they met the following inclusion criteria: age 5 and older, physician-defined persistent asthma, documented ongoing symptoms within the past year, and on treatment with an asthma controller. Patients were excluded if they had any diagnoses other than asthma that might affect pulmonary function; or had acute symptoms at the time of the PFTs. After deidentification, demographic data and all pulmonary function data, before and after inhaled albuterol, were extracted from the most recent pulmonary function test performed by each patient. FEV1 and FVC, expressed as % of predicted values, were recalculated with the 2022 GLI global reference equations11Bowerman C, Bhakta NR, Brazzale D, Cooper BR, Cooper J, Gochicoa-Rangel L, Haynes J, Kaminsky DA, Lan LTT, Masekela R, McCormack MC, Steenbruggen I, Stanojevic S. A Race-neutral Approach to the Interpretation of Lung Function Measurements. Am J Respir Crit Care Med. 2023 Mar 15;207(6):768-774.. Lung volumes and specific airway conductance (sGaw) were estimated with whole body plethysmography22Dubois AB, Botelho SY, Comroe JH Jr. A new method for measuring airway resistance in man using a body plethysmograph: values in normal subjects and in patients with respiratory disease. J Clin Invest. 1956 Mar;35(3):327-35.. Total Lung Capacity (TLC) and Residual Volume (RV) are expressed as % of predicted as determined by standard reference equations33Zapletal A, Chalupová J, Kucera J. Lung volumes in healthy children and adolescents: methods, reference values. Monaldi Arch Chest Dis. 1995 Feb;50(1):6-18.,44Zapletal A, Šamánek M, Paul T. Lung Function in Children and Adolescents. Methods, reference values. Progress in Respiratory Research, Vol. 22, Basel: Karger, 1987.,55Stocks J, Quanjer PH. Reference values for residual volume, functional residual capacity and total lung capacity. ATS Workshop on Lung Volume Measurements. Official Statement of The European Respiratory Society. Eur Respir J. 1995 Mar;8(3):492-506..