Abstract
Background Telemonitoring trials for early detection of acute exacerbations (AECOPD) have provided mixed results. Day-to-day variations in lung function measured by forced oscillation technique (FOT) may yield better insight. We evaluated the clinical utility of home telemonitoring of variability of FOT measures, in terms of (i) relationship with symptoms and quality of life, and (ii) the timing of variability of FOT measures and symptom changes prior to AECOPD.
Methods Daily FOT parameters at 5 Hz (resistance (R) and reactance (X); Resmon Pro Diary, Restech Srl), daily symptoms (COPD Assessment Test, CAT) and 4-weekly quality of life (St. George's Respiratory Questionnaire, SGRQ) were obtained over 8–9 months from COPD patients. Variability of resistance and reactance was calculated as the standard deviation (sd) over 7-day running windows; we also examined the effect of varying window size. The relationships between FOT versus CAT and SGRQ were assessed using linear mixed modelling, daily changes in FOT variability and CAT prior to AECOPD using one-way repeated measures ANOVA.
Results 15 participants with mean(sd) age 69(10) years and FEV1%predicted 39(10) had a median(IQR) adherence of 95.4(79.0–98.8)%. Variability of the inspiratory component of X (SDXinsp) related to CAT and weakly SGRQ (fixed effect estimate(95%CI) 1.57(0.65–2.49), p=0.001 and 4.41(−0.06–8.89), p=0.05, respectively). SDXinsp changed significantly on the same day as CAT (1 day before AECOPD, both p=0.02), and earlier when using shorter running windows (3 days before AECOPD, p=0.01, accuracy=0.72 for 5-day windows).
Conclusions Variability of inspiratory reactance from FOT telemonitoring reflects COPD symptoms and may be a sensitive biomarker to detect AECOPD early.
Footnotes
This manuscript has recently been accepted for publication in the European Respiratory Journal. It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJ online. Please open or download the PDF to view this article.
Conflict of interest: Dr. Zimmermann reports grants from National Health and Medical Research Grant (NHMRC) 1049560, grants from Lung Foundation Australia/Boehringer Ingelheim COPD Research Top Up Grant 2016, other from National Health and Medical Research Grant (NHMRC) Postgraduate Scholarship 1074630, during the conduct of the study; non-financial support from Glaxo-Smith Kline, non-financial support from Boehringer Ingelheim, non-financial support from Astra Zeneca, non-financial support from Menarini, non-financial support from Novartis Pharmaceuticals, outside the submitted work; and The FOT devices used in the study were provided on loan from Restech Srl.
Conflict of interest: Dr. Huvanandana has nothing to disclose.
Conflict of interest: Dr. Nguyen has nothing to disclose.
Conflict of interest: Amy Bertolin has nothing to disclose.
Conflict of interest: Dr. Watts has nothing to disclose.
Conflict of interest: Dr. Gobbi reports other from Restech Srl, outside the submitted work.
Conflict of interest: Dr. Farah reports personal fees from GlaxoSmithKline, personal fees from AstraZeneca, from Boehringer Ingelheim, personal fees from Sanofi Genzyme, outside the submitted work.
Conflict of interest: Dr. Peters has nothing to disclose.
Conflict of interest: Dr. Dellaca’ reports grants from Acutronic, personal fees from Restech srl, outside the submitted work; In addition, Dr. Dellaca’ has a patent on the detection of EFL by FOT with royalties paid to Philips Respironics and Restech srl, a patent on monitoring lung volume recruitment by FOT with royalties paid to Vyaire, and a patent on early detection of exacerbations by home monitoring of FOT with royalties paid to Restech and is co-founder and shareholder of Restech srl, a spin-off company of the Politecnico di Milano University producing medical devices for lung function testing based on FOT.
Conflict of interest: Dr. King reports grants from University of Sydney Bridging Grant, during the conduct of the study; grants, personal fees and other from AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, Novartis, Menarini, MundiPharma, grants from National Health & Medical Research Council, Asthma Foundation., other from ATS and ERS, non-financial support and other from Restech, outside the submitted work.
Conflict of interest: Dr. Thamrin has a patent WO 2006130922 A1 issued and is a member of a current international task force committee on FOT technical standards. In additiona, Dr. Thamrin has intellectual property arrangements with THORASYS Thoracic Medical Systems and Restech srl relating to research collaborations, but does not have any financial relationships with either company.
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- Received September 4, 2019.
- Accepted April 17, 2020.
- Copyright ©ERS 2020