Aims: Home spirometry has increasingly been studied in pulmonary fibrosis, but is not yet widely implemented in regular care. We evaluated the use of home spirometry in regular care, and assessed lung function course in patients with idiopathic pulmonary fibrosis (IPF) and other forms of pulmonary fibrosis (PF).

Methods: In this real-world national multicenter cohort, patients with IPF and PF measured their forced vital capacity (FVC) with online home spirometry. Disease course was classified as stable/slowly progressive when ?FVC decline was < 5%, moderate progressive if ?FVC decline was >5% and <10%, and rapidly progressive if ?FVC decline was >10% over 1 year. Linear mixed models were used to analyze 1-years data.

Results: We analyzed home spirometry data from 373 patients (IPF n=273,PF n=100, median age 72 years (IQR11),79% male) from 9 centers in the Netherlands. Patients had a mean baseline FVC of 3.06L. Mean FVC decline after 1 year was 0.23L. The coefficient of variation was 6%. There was no significant difference between lung function course in patients with IPF and PF (p=0.18). In the IPF group, 41% had a stable/slowly progressive disease course, 31% had a moderate progressive disease course and 28% rapidly progressive. In the PF group, 46% were stable/slowly progressive, 17% moderate progressive and 37% had a rapidly progressive disease course.

Conclusion: Home spirometry is feasible and reliable as part of regular care for patients with IPF and PF. FVC decline measured with home spirometry was comparable to previous studies and real-life cohorts measured with in-hospital spirometry. Interestingly, patients with PF had an IPF-like disease course, which was rapidly progressive in one third of the patients.