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Comparative Study
. 2017 Jul 5;50(1):1602406.
doi: 10.1183/13993003.02406-2016. Print 2017 Jul.

Home monitoring improves endpoint efficiency in idiopathic pulmonary fibrosis

Kerri A Johannson  1   2 , Eric Vittinghoff  3 , Julie Morisset  4 , Joyce S Lee  5 , John R Balmes  6   7 , Harold R Collard  7
Affiliations
Comparative Study

Home monitoring improves endpoint efficiency in idiopathic pulmonary fibrosis

Kerri A Johannson et al. Eur Respir J. .

Abstract

The objective of this study was to investigate the reliability, feasibility and analytical impact of home-based measurement of forced vital capacity (FVC) and dyspnoea as clinical endpoints in idiopathic pulmonary fibrosis (IPF).Patients with IPF performed weekly home-based assessment of FVC and dyspnoea using a mobile hand-held spirometer and self-administered dyspnoea questionnaires. Weekly variability in FVC and dyspnoea was estimated, and sample sizes were simulated for a hypothetical 24-week clinical trial using either traditional office-based interval measurement or mobile weekly assessment.In total, 25 patients were enrolled. Mean adherence to weekly assessments over 24 weeks was greater than 90%. Compared with change assessment using baseline and 24-week measurements only, weekly assessment of FVC resulted in enhanced precision and power. For example, a hypothetical 24-week clinical trial with FVC as the primary endpoint would require 951 patients using weekly home spirometry compared with 3840 patients using office spirometry measures at weeks 1 and 24 only. The ability of repeated measures to reduce clinical trial sample size was influenced by the correlation structure of the data.Home monitoring can improve the precision of endpoint assessments, allowing for greater efficiency in clinical trials of therapeutics for IPF.

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Conflict of interest statement

Conflict of interest: Disclosures can be found alongside this article at erj.ersjournals.com

Figures

FIGURE 1
FIGURE 1
Bland–Altman plot comparing baseline office-based and hand-held spirometry. FVC: forced vital capacity.
FIGURE 2
FIGURE 2
Adherence to home spirometry. a) Mean adherence over the study period. Black lines indicate measurements recorded between weeks 1 and 24, grey lines indicate measurements recorded between weeks 24 and 40. b) Percentage of patients adherent over the study period.
FIGURE 3
FIGURE 3
Individual weekly variability in forced vital capacity (FVC) over the study period.
FIGURE 4
FIGURE 4
Weekly home measurements demonstrating correlation structures. a) Hand-held forced vital capacity (FVC) measures over time for two simulated patients typical of the sample. The circles represent each weekly FVC measure and the dotted lines represent the individual’s modelled linear trajectory over 24 weeks. These plots demonstrate a compound symmetrical correlation structure: that is, the correlation between any two measures within an individual is independent of the time lag between the two measures. b) Home dyspnoea visual analogue scale (VAS) scores over time for two simulated patients typical of the sample. The circles represent each weekly VAS measure and the dotted lines represent the individual’s modelled linear trajectory over 24 weeks. The plots demonstrate a declining correlation structure: that is, the correlation between any two measures within an individual decreases as the time between the two measures increases.
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Comment in

References

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