The TACTICAS study, published in ERJ Open Research, identified changes in voice recordings from mobile phones that signal respiratory exacerbation onset in individuals with asthma and chronic obstructive pulmonary disease (COPD).

The study included 73 participants recruited from respiratory clinics. Of these participants, 35 had asthma and 38 had COPD. Participants, with a mean age of 62 years, recorded their voices three times daily for three months using mobile phones. The TACTICAS app prompted speech recordings with a sustained vowel sound and either a paragraph reading or an answer to a question. Recordings were made in the morning, after a light exercise task in the afternoon, and in the evening, alongside symptom questionnaires.

Researchers used the validated EXACT questionnaire to detect exacerbations, defined by an increase in symptom score of more than nine points from baseline for three days or over 12 points for two consecutive days. They checked in with participants every four weeks. Data on medication or symptom increases were stored in the electronic Case Record Form (eCRF). Exacerbations were clinically verified using electronic health records (EHR), medication use, and patient-reported symptoms.

The TACTICAS study collected 23,799 voice recordings in total, with 2,737 of these occurring during exacerbations. Among these, 227 recordings were made on the day an exacerbation began, peaked, or recovered. The study captured 38 exacerbations, most of which were mild to moderate.

Analysis revealed measurable changes in speech on the first day of an exacerbation. Multilevel analysis identified 13 acoustic speech features that changed at exacerbation onset. These included a lower median pitch, shorter sustained vowel sounds, and greater shimmer, along with an increased Noise-to-Harmonics Ratio. Voice changes evolved throughout the exacerbation period, from onset through peak symptoms to recovery. Shimmer and the Noise-to-Harmonics Ratio showed a stronger association with chest symptoms, while minimum pitch was more closely related to breathlessness. Voice changes were similar in participants with asthma and those with COPD. Maximum voice pitch increased as participants recovered from an exacerbation. Participants were observed to be less likely to complete symptom questionnaires when they felt unwell.

Why It Matters

The study describes a method for detecting respiratory exacerbations in patients with asthma and COPD using mobile technology. By identifying specific voice changes that correlate with the onset and progression of exacerbations, the findings could contribute to the development of non-invasive monitoring tools. The TACTICAS study authors state that the findings are exploratory and require confirmation in larger studies to establish broader applicability.