Abstract
Background Cough represents a cardinal symptom of acute respiratory tract infections. Generally associated with disease activity, cough holds biomarker potential and might be harnessed for prognosis and personalized treatment decisions. Here, we tested the suitability of cough as a digital biomarker for disease activity in COVID-19 and other lower respiratory tract infections.
Methods We conducted a single-center, exploratory, observational cohort study on automated cough detection in patients hospitalized for COVID-19- (n=32) and non-COVID-19 pneumonia (n=14) between April and November 2020 at the Cantonal Hospital St.Gallen, Switzerland. Cough detection was achieved using smartphone-based audio recordings coupled to an ensemble of convolutional neural networks. Cough levels were correlated to established markers of inflammation and oxygenation.
Measurements and main results Cough frequency was highest upon hospital admission and declined steadily with recovery. There was a characteristic pattern of daily cough fluctuations, with little activity during the night and two coughing peaks during the day. Hourly cough counts were strongly correlated with clinical markers of disease activity and laboratory markers of inflammation, suggesting cough as a surrogate-of-disease in acute respiratory tract infections. No apparent differences in cough evolution were observed between COVID-19- and non-COVID-19 pneumonia.
Conclusions Automated, quantitative, smartphone-based detection of cough is feasible in hospitalized patients and correlates with disease activity in lower respiratory tract infections. Our approach allows for near real-time telemonitoring of individuals in aerosol isolation. Larger trials are warranted to decipher the use of cough as a digital biomarker for prognosis and tailored treatment in lower respiratory tract infections.
Footnotes
This manuscript has recently been accepted for publication in the ERJ Open Research. 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 ERJOR online. Please open or download the PDF to view this article.
Conflict of interest: Three of the authors (PT, IS, DC) have co-founded or hold shares of Resmonics AG, Zurich, Switzerland.
Conflict of interest: The other authors have no conflicts of interest to declare. No medical writer was involved in the preparation of the manuscript.
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- Received October 5, 2022.
- Accepted February 15, 2023.
- Copyright ©The authors 2023
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