Clinic vs Home Spirometry for Monitoring Lung Function in Patients With Asthma

Background: Studies examining agreement between home and clinic spirometry in patients with asthma are limited, with conflicting results. Understanding the strengths and limitations of telehealth and home spirometry is particularly important considering the SARS-CoV-2 pandemic.

Research question: How well do home and clinic measurements of trough FEV₁ agree in patients with uncontrolled asthma?

Study design and methods: This post hoc analysis used trough FEV₁ data from the randomized double-anonymized parallel-group phase 3A CAPTAIN (205715; NCT02924688) and phase 2B 205832 (NCT03012061) trials in patients with uncontrolled asthma. CAPTAIN evaluated the impact of adding umeclidinium to fluticasone furoate/vilanterol via a single inhaler; the 205832 trial investigated adding umeclidinium to fluticasone furoate vs placebo. Trough FEV₁ measurements were collected via home spirometry and supervised in-person spirometry in the research clinic. To compare home and clinic spirometry, we examined the time-course analyses of home and clinic trough FEV₁, and generated post hoc Bland-Altman plots to assess agreement between home and clinic spirometry.

Results: Data from 2,436 patients (CAPTAIN trial) and 421 patients (205832 trial) were analyzed. Treatment-related improvements in FEV₁ were observed in both trials, using home and clinic spirometry. Improvements measured by home spirometry were of lower magnitude and less consistent than clinic measurements. Bland-Altman plots suggested poor agreement between home and clinic trough FEV₁ at baseline and week 24.

Interpretation: This post hoc comparison of home and clinic spirometry is the largest conducted in asthma. Results showed that home spirometry was less consistent than and lacked agreement with clinic spirometry, suggesting that unsupervised home readings are not interchangeable with clinic measurements. However, these findings may only be applicable to home spirometry using the specific device and coaching methods employed in these studies. Postpandemic, further research to optimize home spirometry use is needed.

Clinical trial registration: ClinicalTrials.gov; Nos.: NCT03012061 and NCT02924688; URL: www.

Clinicaltrials: gov.