Daily home-based spirometry during withdrawal of inhaled corticosteroid in severe to very severe chronic obstructive pulmonary disease

Abstract

The WISDOM study (NCT00975195) reported a change in lung function following withdrawal of fluticasone propionate in patients with severe to very severe COPD treated with tiotropium and salmeterol.However, little is known about the validity of home-based spirometry measurements of lung function in COPD.Therefore, as part of this study, following suitable training, patients recorded daily home-based spirometry measurements in addition to undergoing periodic in-clinic spirometric testing throughout the study duration.We subsequently determined the validity of home-based spirometry for detecting changes in lung function by comparing in-clinic and home-based forced expiratory volume in 1 second in patients who underwent stepwise fluticasone propionate withdrawal over 12 weeks versus patients remaining on fluticasone propionate for 52 weeks.Bland-Altman analysis of these data confirmed good agreement between in-clinic and home-based measurements, both across all visits and at the individual visits at study weeks 6, 12, 18, and 52.There was a measurable difference between the forced expiratory volume in 1 second values recorded at home and in the clinic (mean difference of -0.05 L), which may be due to suboptimal patient effort in performing unsupervised recordings.However, this difference remained consistent over time.Overall, these data demonstrate that home-based and in-clinic spirometric measurements were equally valid and reliable for assessing lung function in patients with COPD, and suggest that home-based spirometry may be a useful tool to facilitate analysis of changes in lung function on a day-to-day basis.