Objective markers for asthma-like coughs can be measured via smartphone without additional effort for patients. This technology could solve the current problems in monitoring respiratory diseases.1
Can data recorded by smartphones be used to detect asthma attacks or to make meaningful changes in asthma control? This was investigated in a study of 79 adult asthma patients. "Until now, we did not have a reliable tool to measure people's asthma symptoms overnight, so we know very little about nocturnal coughing and its significance," said Dr. Frank Rassouli (Kantonsspital St.Gallen, Switzerland).
Smartphones have great potential to monitor different symptoms and detect changes early. That is why Dr. Rassouli, together with research partners from the University of St. Gallen and ETH Zurich, have developed an app for measuring coughs.
The participants were treated at two clinics in Switzerland: the Lung Centre of the Kantonsspital St.Gallen and the Medix Gruppenpraxis team in Zurich. All participants visited their clinics at the beginning and end of the study and were examined with regard to the use of asthma treatments, the symptoms, and the effects of asthma on their daily lives. All patients documented their sleep quality and the frequency of night-time coughing on a daily basis using the Pittsburgh Sleep Quality Index (PSQI). In addition, sensor data from smartphones were collected onsite for 29 days. The patients slept while the app recorded the nightly cough acoustically. The app also asked participants to report their nocturnal symptoms.
Asthma was controlled for 192 weeks and not controlled for 116 weeks. A clinically significant worsening occurred in 25 patients at 29 weeks. Mixed regression analyses showed: nocturnal coughing and sleep quality at both inter- and intra-patient levels were statistically significantly associated with asthma control (P<0.05). Decision trees showed that sleep quality was a useful indicator to detect periods of uncontrolled asthma, while the deterioration in asthma control was particularly well detected by nocturnal coughing.
Dr. Rassouli explained: "Our results suggest that night-time cough can be measured fairly easily with a smartphone app and that an increase in night-time cough is an indicator that asthma is getting worse. Monitoring asthma is really important. Because if we can see early on that it is getting worse, we can adjust the medication to prevent asthma attacks". Cut-offs with both markers predicted asthma attacks up to 5 days in advance with an accuracy rate between 70% and 75% (sensitivities 75-88% and specificities 57%-72%).
Because the smartphone app has been so successfully used to monitor coughs in people with asthma, Dr. Rassouli and his team want to test the same technology in people with chronic obstructive pulmonary disease.
1. Rassouli F, et al Smartphone-based cough detection predicts asthma control - description of a novel, scalable digital biomarker. Abstract OA4569, ERS International Virtual Congress 2020, 7-9 Sept.