Longitudinal follow-up of spirometry parameters in patients with COPD during pulmonary rehabilitation

<bold>Background:</bold> Spirometry is pivotal in the diagnosis and classification of COPD. There is limited data regarding variation in daily spirometry measurements in COPD. <bold>Objectives:</bold> This study investigated daily variation per week in spirometry parameters in patients with COPD during an 8-week inpatient pulmonary rehabilitation (PR) programme. <bold>Methods:</bold> Data of the first 30 participants of the ongoing “early diagnostic bioMARKers in Exacerbations of COPD” (MARKED) study (<ext-link>NCT05315674</ext-link>) in Ciro (Horn, The Netherlands) were analyzed. Spirometries were performed five days a week (Monday-Friday), during eight weeks. Values of the forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/FVC ratio and peak expiratory flow (PEF) were captured. To test variations of daily spirometry results within individuals per week, during the eight-week PR period, the Friedman test and the post-hoc 2-way ANOVA analysis were performed, excluding dropouts. <bold>Results:</bold> At baseline, patients (60% males, aged 69±7.3 years) had an average of FEV1: 35.9±16.5% pred, FVC: 83.0±21.5% pred, FEV1/FVC: 33.6±10.4% and PEF: 57.4±15.8% pred. No significant differences in spirometry measurements were observed within individuals per week, during 8-week PR. Nine patients (30%) dropped out mainly due to the burden of daily spirometry (89%). <bold>Conclusions:</bold> This study demonstrated no significant differences in daily spirometry measurements within patients with COPD on a weekly basis during eight-weeks of PR. Results of the MARKED and other studies are needed to validate these findings.