A prospective cohort study, TACTICAS, identified measurable changes in speech that correlated with exacerbations of asthma and chronic obstructive pulmonary disease (COPD). The study found that these voice changes, detectable via smartphone, were present on the first day of an exacerbation and evolved throughout the exacerbation period.

The TACTICAS study, an acronym for Telemonitoring for Asthma and COPD Through voICe AnalysiS, was published in the journal ERJ Open Research. The study included 73 participants recruited at respiratory clinics, with a mean age of 62 years. Of the participants, 35 had asthma and 38 had COPD.

Participants recorded their voice three times a day for three months using their own mobile phones. The TACTICAS app, co-created with asthma and COPD patients and designed for home use, prompted speech recordings in the morning, after light exercise in the afternoon, and in the evening, alongside symptom questionnaires. Voice capture methods included a sustained vowel sound and either a paragraph reading or an answer to a question.

Exacerbations were detected using the validated EXACT questionnaire, defined as an increase in symptom score by over nine points from baseline for three days, or scoring over 12 points for two consecutive days. Researchers checked in with participants every four weeks. Exacerbations were clinically verified using electronic health records (EHR) in combination with medication use and patient-reported symptoms. Data on medication or symptom increase were stored in the electronic Case Record Form (eCRF). Only validated exacerbation events were included in the analysis. Events not reported by participants but identified by eCRF or EHR analysis were also included.

The study obtained 23,799 voice recordings in total, with 2,737 recordings occurring during exacerbations. There were 227 recordings made on the day of onset, recovery, or peak of an exacerbation. The study captured 38 exacerbations, most of which were mild and moderate, and most were captured by the questionnaire. Multilevel analysis identified 13 acoustic speech features that showed changes at the onset of an exacerbation. These included a lower median pitch, shorter sustained vowel sounds, and greater shimmer, an indicator of irregular vocal-fold vibrations. The Noise-to-Harmonics Ratio also increased during exacerbations.

Voice changes were similar in participants with asthma and those with COPD. Shimmer and the Noise-to-Harmonics Ratio were more strongly associated with chest symptoms, while minimum pitch showed a stronger relationship with breathlessness. Maximum voice pitch increased as participants recovered. Participants were less likely to complete symptom questionnaires when they felt unwell.

The study indicates that vocal biomarkers can offer a non-invasive method for the early detection of exacerbations in asthma and COPD patients. The ability to monitor voice changes through a smartphone app suggests a potential for remote patient monitoring, especially since participants were less likely to complete symptom questionnaires when feeling unwell. The identified acoustic features and their correlation with specific symptoms provide a basis for developing diagnostic tools.