Correlation of digital flow peak with spirometry in children with and without asthma.

INTRODUCTION: Spirometry and peak expiratory flow measurement (PEF) are combined during functional respiratory assessments. The new digital peak flow meter (DPM) evaluates the forced expiratory volume in the first second (FEV1) and PEF. OBJECTIVE: To compare lung function measurements using spirometry and DPM. METHODS: This cross-sectional analytical study assessed FEV1 and PEF in children with and without asthma. Statistical analysis was performed to assess the agreement between the measures using the intraclass correlation coefficient (ICC), Bland-Altman, and survival agreement plot. RESULTS: 125 (3-12 y) and 196 (6-18 y) children without and with asthma, respectively, were studied. In children without asthma, the ICC for FEV1 and PEF were 0.89 and 0.86, respectively, while the corresponding values were 0.87 and 0.79, respectively, in patients with asthma. The Bland-Altman method showed a difference of -0.4 to 0.5 for FEV1 in patients without asthma, with a tendency to increase as the FEV1 increased to a certain extent. In patients with asthma, the pattern was similar for FEV1, and the PEF had a greater dispersion than among those without asthma; however, a good agreement pattern was maintained. In the survival agreement plot, when accepting a tolerance of 0.150 mL for FEV1, there was an agreement of close to 55% in both groups. Likewise, when accepting a tolerance of 0.5 L/s for PEF, an agreement of close to 60% and 50% was observed in patients without and with asthma, respectively. CONCLUSION: DPM was effective as a measure of lung function in pediatric patients with and without asthma.