This study is to evaluate the efficacy of the digital health assistant (DHA) "Alex" in improving asthma control in asthmatic children and adolescents aged 10 to 19 compared to their baseline values. It is designed to track over a period of six consecutive months lung function parameters, lung inflammation, asthma symptoms and burden, medication adherence, and passively recorded nocturnal asthma symptoms and markers related to sleep quality.

In Phase I (months 1-3), Digital Health Assistant (DHA) 's core functionality will be deployed.

In Phase II (months 3-6), the platform will be augmented with lung-function-fluctuations analysis-informed therapeutic recommendations, allowing to quantify the incremental benefit of targeted decision support beyond the gamified DHA alone.

An embedded qualitative study will be conducted to evaluate acceptability of and engagement with the DHA.

This cohort study is designed to track over a period of six consecutive months lung function parameters, lung inflammation, asthma symptoms and burden, medication adherence, and passively recorded nocturnal asthma symptoms and markers related to sleep quality. The study is comprised of two phases:

In Phase I (months 1-3), Digital Health Assistant (DHA) 's core functionality will be deployed, i.e., active collection of daily lung function, and fortnightly administration of the Asthma Control Questionnaire (ACQ), together with passive monitoring of controller asthma medication use and nocturnal physiological metrics (respiratory rate, SpO₂, heart rate, cough frequency) via inhaler sensor, smartwatch and bedside microphone. Moreover, Digital Health Assistant will act as an engagement/adherence enhancing patient coach, providing behavioral economics informed reminders and incentives, and educational materials on asthma and asthma treatment. This phase will enable to determine the effect of these core features of the Digital Health Assistant on asthma control.

In Phase II (months 3-6), the platform will be augmented with lung-function-fluctuations analysis-informed therapeutic recommendations, allowing to quantify the incremental benefit of targeted decision support beyond the gamified DHA alone.

In addition, an embedded qualitative study will be conducted to evaluate acceptability of and engagement with the DHA. This will include in-depth interviews (IDIs) with adolescents and focus group discussions (FGDs) with adolescents and healthcare providers.

Observational study population:

Inclusion Criteria:

• Written informed assent or consent, and parental/caregivers consent, depending on age.
• Age 10 to 19 years.
• Sufficient understanding of the Romanian language.
• Digital literacy, including the parents/caregivers, as assessed by the treating physician and/or by the recruiting healthcare provider using a multiple-choice questionnaire administered to the patient and their parents after a brief introduction to the functionalities of the Alex app.
• Confirmed asthma, i.e., history of recurrent wheeze, at least one spirometry in the three years prior to inclusion showing reversible obstruction (increase in forced expiratory volume at one second (FEV1) of ≥12% and/or ≥200ml) and/or a positive airway challenge test142.
• Participants need to be under treatment with regular prescribed asthma drugs, including inhaled corticosteroids, Long-acting β adrenoceptor agonists (LABA), and/or leukotriene receptor antagonists at recruitment, with no change in their medication in the last month.

Exclusion Criteria:

• Inability to perform adequate lung function measurements due to physical and/or intellectual disability.
• Acute asthma exacerbation requiring systemic corticosteroids within four weeks prior to recruitment.
• Not willing to use smartphones.
• Underlying chronic respiratory disease other than asthma (cystic fibrosis, primary ciliary dyskinesia).
• Acute lower respiratory tract infections (e.g., pneumonia, bronchitis) diagnosed by physician within past 4 to 6 weeks. For tuberculosis, see next exclusion criterion.
• Active tuberculosis as per Quantiferon test.
• Other causes of nocturnal cough such as postnasal drip, and vocal cord dysfunction.
• Active smoking as per urinary Cotinin test.
• Substance abuse as per urinary drug test.

Qualitative study population:

Inclusion criteria:

• Enrolled in the observational study
• Have had access to the DHA for at least 6 weeks
• Provide informed assent (and parental/guardian consent where applicable) or consent, according to age
• Able to participate in interviews or group discussions in Romanian

Exclusion criteria:

• Significant cognitive or communication difficulties that would limit participation in interviews or group discussions
• Withdrawn from the observational study prior to data collection for qualitative work

Adolescents, age 10 to 19 years, attending tertiary referral asthma clinics in the Romanian cities Brasov, Bucharest, Timisoara, and Suceava.

For the Qualitative Substudy (IDIs and focus group discussions with adolescents), a sub-sample of participants from the observational study will be recruited, purposively selected to include roughly equal numbers of younger (10-14) and older (15-19) adolescents, as well as including both those that are identified as having higher and lower engagement, based on the app usage data.