Comparison of three digital peak expiratory flow devices with spirometry in children and adolescents with asthma

We compared lung function measurements of three digital peak flow meters (DPMs) to those from spirometry pre and post-bronchodilation (BD). We conducted a cross-sectional analysis in patients with asthma between 6 to 18 years, evaluating three DPMs: Microlife, Piko, and Asthma-1. We assessed the agreement between measurements using paired t-tests, intraclass correlation coefficients (ICC), Bland–Altman plots, and survival–agreement plots. The ICCs for peak expiratory flow (PEF) were 0.756 (pre-BD) and 0.762 (post-BD). The spirometry mean was 3.63L/sec, and differences were observed for Microlife (−0.13; p = 0.025), Piko (−0.36; p < 0.001), and Asthma-1 (−0.38; p < 0.001); with similar trends in post-BD. The pre-BD spirometric mean was 1.83L for forced expiratory volume in 1s (FEV1), with significant difference for Microlife (−0.14), Piko (−0.21), and Asthma-1 (−0.30) (all p < 0.001). The corresponding pre-BD ICC was 0.762, with similar results observed post-BD. Bland–Altman analysis for PEF revealed pre-BD differences for Microlife (+2 to −3), Piko (+5 to −4), and Asthma-1 (+2 to −3). Post-BD results showed no change for Microlife and Piko. However, for Asthma-1, a difference of +2 to −4 was observed. FEV1, differences for Microlife ranged from +0.75 to −1.5 (pre-BD) and +0.5 to −1.5 (post-BD) were observed. Piko ranges were +5.5 to −1.5 (pre-BD) and +4.5 to −2.5 (post-BD); Asthma-1 ranges were +0.5 to −1.5 (pre-BD) and +0.25 to −1.75 (post-BD). Similar results were obtained using the survival–agreement. All DPMs showed moderate agreement with spirometry, with the Microlife device demonstrated comparatively greater accuracy.