Longitudinal passive cough monitoring and its implications for detecting changes in clinical status

Juan C Gabaldón-Figueira; Eric Keen; Matthew Rudd; Virginia Orrilo; Isabel Blavia; Juliane Chaccour; Mindaugas Galvosas; Peter Small; Simon Grandjean Lapierre; Carlos Chaccour

doi:10.1183/23120541.00001-2022

Longitudinal passive cough monitoring and its implications for detecting changes in clinical status

ERJ Open Res. 2022 May 16;8(2):00001-2022. doi: 10.1183/23120541.00001-2022. eCollection 2022 Apr.

Authors

Juan C Gabaldón-Figueira¹, Eric Keen², Matthew Rudd^{2

3}, Virginia Orrilo⁴, Isabel Blavia⁴, Juliane Chaccour¹, Mindaugas Galvosas², Peter Small^{2

5}, Simon Grandjean Lapierre^{6

7

8}, Carlos Chaccour^{1

9

10

8}

Affiliations

¹ Dept of Microbiology and Infectious Diseases, Clinica Universidad de Navarra, Pamplona, Spain.
² Research and Development Dept, Hyfe Inc, Wilmington, DE, USA.
³ Dept of Mathematics and Computer Science, The University of the South, Sewanee, TN, USA.
⁴ School of Pharmacy and Nutrition, University of Navarra, Pamplona, Spain.
⁵ Dept of Global Health, University of Washington, Seattle, WA, USA.
⁶ Immunopathology Axis, Research Center of the University of Montreal Hospital Center, Montréal, QC, Canada.
⁷ Dept of Microbiology, Infectious Diseases and Immunology, Research Center of the University of Montreal Hospital Center, Montreal, QC, Canada.
⁸ These authors contributed equally.
⁹ Centro de Investigación Biomédica en Red de Enfermedades Infecciosas, Madrid, Spain.
¹⁰ ISGlobal, Hospital Clinic, University of Barcelona, Barcelona, Spain.

Abstract

Research question: What is the impact of the duration of cough monitoring on its accuracy in detecting changes in the cough frequency?

Materials and methods: This is a statistical analysis of a prospective cohort study. Participants were recruited in the city of Pamplona (Northern Spain), and their cough frequency was passively monitored using smartphone-based acoustic artificial intelligence software. Differences in cough frequency were compared using a one-tailed Mann-Whitney U test and a randomisation routine to simulate 24-h monitoring.

Results: 616 participants were monitored for an aggregated duration of over 9 person-years and registered 62 325 coughs. This empiric analysis found that an individual's cough patterns are stochastic, following a binomial distribution. When compared to continuous monitoring, limiting observation to 24 h can lead to inaccurate estimates of change in cough frequency, particularly in persons with low or small changes in rate.

Interpretation: Detecting changes in an individual's rate of coughing is complicated by significant stochastic variability within and between days. Assessing change based solely on intermittent sampling, including 24-h, can be misleading. This is particularly problematic in detecting small changes in individuals who have a low rate and/or high variance in cough pattern.