Digital markers of asthma exacerbations: a systematic review.

Background and objective: With the increase in use of digital technologies, there is growing interest in digital markers, where technology is used to detect early markers of disease deterioration. The aim of this systematic review is to summarise the evidence relating to digital markers of asthma exacerbations.

Methods: A systematic search of the following databases was conducted, using key search terms relating to asthma, digital and exacerbations: Ovid MEDLINE, EMBASE, Psycinfo, Cochrane Database of Systematic Reviews and Cochrane Central Register of Controlled Trials. Studies that aimed to explore the relationship between any digitally measured marker and asthma exacerbations using any form of portable digital sensor technology were included.

Results: 23 papers were included. The digital markers related to five key categories: environmental, physiological, medication, lung function and breath-related parameters. The most commonly studied marker was lung function, which was reported in over half (13 out of 23) of the papers. However, studies were conflicting in terms of the use of lung function parameters as a predictor of asthma exacerbations. Medication parameters were measured in over a third of the studies (10 out of 23) with a focus on short-acting β-agonist (SABA) use as a marker of exacerbations. Only four and two studies measured heart rate and cough, respectively; however, both parameters were positively associated with exacerbations in all reported studies.

Conclusion: Several digital markers are associated with asthma exacerbations. This suggests a potential role for using parameters such as heart rate, SABA use and, potentially, cough as digital markers of asthma exacerbations.