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Validating Remote FEV1 Monitoring in Moderate Asthmatics to Increase Study Power

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A3934 - Validating Remote FEV1 Monitoring in Moderate Asthmatics to Increase Study Power
Author Block: G. Bhatia1, M. Ruddy2, N. Jackson3, D. Singh4; 1Koneksa Health, New York, NY, United States, 2Regeneron Pharmaceuticals, Tarrytown, NY, United States, 3Medicines Evaluation Unit, University of Manchester, Manchester, United Kingdom, 4Medicines Evaluation Unit, Univ Hosp Of South Manchester, Manchester, United Kingdom.
Remote FEV1 monitoring using digital spirometers provides an opportunity to collect repeated measures of lung function with minimum of disruption to everyday life. In the context of clinical trials, these repeated measures may improve power to detect treatment effects by reducing standard error of the measure. However, it is not clear if patients would be able to generate high quality spirometry data by this method. The aim of this study was to qualify remote spirometry for use in clinical trials of asthma patients.
We recruited 12 patients with moderate asthma, aged between 18-55 years, to participate in a single-centre study performed at the University Hospital of South Manchester. Subjects were instructed to perform spirometry at home using the mSpirometer twice daily (06:00-10:00 and 18:00-22:00) for 28 days. The max FEV1 for 3 forced expiratory manoeuvres was recorded. Subjects also performed spirometry in the clinic at weekly intervals (every 7 days).
The mean compliance with at-home spirometry was 77% (SD 19%) corresponding to a total of 527 at-home readings. Subjects contributed at least one measurement on 84% of study days. In-clinic measurements of FEV1 were strongly correlated with at-home measurements from both the same morning (r = 0.98; see Figure 1) and same evening (r = 0.94). While at-home FEV1 from the same morning was lower than in-clinic FEV1 (difference = 0.20 L; 95% LOA [-0.15 L, 0.54 L]), we demonstrate diurnal effects drive this bias (i.e. morning FEV1 is typically lower), and provide methodology to correct it. At-home FEV1 from the same afternoon did not show any statistically significant bias.
FEV1 determined by at-home spirometry had a high level of reliability (WSSD = 0.19 L/min) with respect to in-clinic FEV1 (WSSD = 0.20 L/min). Furthermore,
averaging consecutive at-home measures achieved significantly increased reliability (Average of 5 FEV1 values: WSSD = 0.13 L/min), translating into improved study power. In a typical study with change in FEV1 as an endpoint we would need to include 100 individuals per arm in a study to have 90% power to detect a treatment effect of 0.1 L/min. We demonstrate that similar study that used the change in the average at-home FEV1 as an endpoint would require only 18 individuals to be equivalently powered. This dramatic reduction in sample size requirements may enable treatment effect detection in early phase clinical studies.
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