Abstract
BackgroundFibrotic interstitial lung disease (ILD) is often associated with poor outcomes, but has few predictors of progression. Daily home spirometry has been proposed to provide important information about the clinical course of idiopathic pulmonary disease (IPF). However, experience is limited, and home spirometry is not a routine component of patient care in ILD. Using home spirometry, we aimed to investigate the predictive potential of daily measurements of forced vital capacity (FVC) in fibrotic ILD.MethodsIn this prospective observational study, patients with fibrotic ILD and clinical progression were provided with home spirometers for daily measurements over 6 months. Hospital based spirometry was performed after three and 6 months. Disease progression, defined as death, lung transplantation, acute exacerbation or FVC decline > 10% relative was assessed in the cohort.ResultsFrom May 2017 until August 2018, we included 47 patients (IPF n = 20; non-IPF n = 27). Sufficient daily measurements were performed by 85.1% of the study cohort. Among these 40 patients (IPF n = 17; non-IPF n = 23), who had a mean ± SD age of 60.7 ± 11.3 years and FVC 64.7 ± 21.7% predicted (2.4 ± 0.8 L), 12 patients experienced disease progression (death: n = 2; lung transplantation: n = 3; acute exacerbation: n = 1; FVC decline > 10%: n = 6). Within the first 28 days, a group of patients had high daily variability in FVC, with 60.0% having a variation ≥5%. Patients with disease progression had significantly higher FVC variability than those in the stable group (median variability 8.6% vs. 4.8%; p = 0.002). Cox regression identified FVC variability as independently associated with disease progression when controlling for multiple confounding variables (hazard ratio: 1.203; 95% CI:1.050–1.378; p = 0.0076).ConclusionsDaily home spirometry is feasible in IPF and non-IPF ILD and facilitates the identification of FVC variability, which was associated with disease progression.
Highlights
Fibrotic interstitial lung disease (ILD) is often associated with poor outcomes, but has few predictors of progression
These 40 patients participated for a mean ± standard deviation (SD) of 161 ± 38 days in the study, performing home spirometry measurements on a mean of 81.8 ± 18.4% days and 98.4 ± 3.5% of these measurements were of good quality
FVC variability was assessed over 28 days Definition of abbreviations: CI confidence interval, FVC forced vital capacity was a significant predictor for disease progression in the regression analysis with the covariates baseline FVC, age and gender (HR: 1.290; 95%-CI: 1.013–1.643; p = 0.039)
Summary
Fibrotic interstitial lung disease (ILD) is often associated with poor outcomes, but has few predictors of progression. Home spirometry has been proposed to provide important information about the clinical course of idiopathic pulmonary disease (IPF). Experience is limited, and home spirometry is not a routine component of patient care in ILD. We aimed to investigate the predictive potential of daily measurements of forced vital capacity (FVC) in fibrotic ILD. Interstitial lung disease (ILD) is a term for a group of conditions including idiopathic pulmonary fibrosis (IPF). Fibrotic ILD such as IPF are all characterized by fibrotic destruction of the lung parenchyma but with great heterogeneity with respect to clinical presentation and prognosis. Fibrotic ILD suffer from major reductions in quality of life and poor survival, similar to certain malignancies [4]. A reduced forced vital capacity (FVC) has been shown to be the most reliable risk factor for disease progression [5, 6]; in IPF a FVC decline of 5–10% over 6 months is associated with an increased risk of mortality [6]
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