Participants eligible to enroll will be provided with the OnTrackCF app (intervention), and will use the app for 4-12 weeks before completing feasibility measures and a qualitative interview.

OnTrackCF is a mHealth application co-developed with Upstream Dream. It is designed specifically to track and support adherence to CFTR modulator therapy. The app allows users to track their modulator intake and disease symptoms while supporting their adherence goals using Behavioral Change Techniques (BCTs) with empirical evidence of efficacy. The BCTs are administered primarily in the form of messages designed to deliver specific BCTs. The app sends up to 3 adherence support messages per day and provides detailed data to the user about their adherence levels, adherence goals, and disease symptoms. This process will continue until we reach an N=60 AWCF enrolled OR demonstrate that we have achieved 12 weeks of sustained user engagement with the app.

By the last round of testing, the System Usability Survey (SUS) will have a median score of 75%.

By the last round of testing, the Intervention Feasibility and Acceptability (iFAQ) OnTrackCF scales (Engagement, Feasibility, Acceptability, Usefulness, and Satisfaction) will each have a median score of ≥4 (out of 5).

By the last round of testing, 90% of participants will complete the app onboarding process.