Supplementary Material for: Breathing dysfunction as a meaningful and measurable aspect of health in Rett Syndrome: A caregiver's perspective

Introduction: Incorporating outcome measures that assess the most impactful symptoms is a priority for clinical trials. We qualitatively examined whether caregivers of individuals with Rett Syndrome deemed breathing dysfunction as a meaningful and measurable aspect of health. Methods: We conducted semi-structured interviews (N = 13) with caregivers of individuals with Rett syndrome followed by thematic analysis grounded in theory to examine themes. Results: Themes and sub-themes for experiences with breathing dysfunction emerged: (1) meaningfulness; (2) impact; and (3) connecting with other symptoms. Two themes for preferences for digitally measuring breathing dysfunction emerged: (1) conditional willingness; and (2) benefits of digital measurement. Conclusion: Caregivers reported that breathing dysfunction was meaningful and measurable and had significant impacts on their child’s lives as well as theirs and their families. This study lays the groundwork for guiding the development of novel measures and outcomes within future clinical trials managing breathing dysfunction.