Variability of forced vital capacity in progressive interstitial lung disease: a prospective observational study

Abstract

Background Fibrotic 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. Methods In 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. Results From 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). Conclusions Daily home spirometry is feasible in IPF and non-IPF ILD and facilitates the identification of FVC variability, which was associated with disease progression.

Home monitoring of physiology and symptoms to detect interstitial lung disease exacerbations and progression: a systematic review

“…In the study by Johannson et al [22] mean adherence to three times weekly home FVC monitoring over 24 weeks was 90.5% (SD=18.3). The Veit et al [34] study reported that adherence to three times daily home spirometry decreased over time. Median adherence dropped within the first 28 days and decreased from 90% to 81% over six months.…”

“…Most participants were able to provide daily readings, with at least four every five days, for up to 1 year [32,33,41,46]. In contrast, Veit et al [34] and Marcoux et al [30] required patients to perform three spirometry manoeuvres every day and found it feasible. In summary, regular home measurement of FVC in the context of a clinical study was found to be feasible.…”

“…Patients showed a positive attitude towards home monitoring techniques despite differences in age and the size of studies. Ease of use and friendliness of technology contributed to good compliance among patients and their acceptance of the home monitoring systems [34].…”

“…Adherence was calculated by the number of home measurements divided by the number of weeks enrolled in the study for weekly measurements, and number of home measurements divided by the number of days enrolled in the study for daily measurements [22,34]. In the study by Johannson et al [22] mean adherence to three times weekly home FVC monitoring over 24 weeks was 90.5% (SD=18.3).…”

“…In summary, adherence to a home monitoring program varied depending on study duration, frequency of measurement, and transmission. However, nine studies [22,30,32,34,41,42,46,47,49] reported that mean adherence to home spirometry was greater than >75%. Veit et al [34] reported that the decrease adherence with time might be due to lack of reminders to perform spirometry.…”