504 Development and Pilot Test of a Palliative Care Interview Guide for Children with Cystic Fibrosis: the ADAPT-Cystic Fibrosis

refined using an iterative consensus process.Themes were operationalized into codes, and transcripts were coded.Twenty percent of transcripts were double coded, with discrepancies resolved via consensus.Results: One hundred fourteen participants completed interview 1 (68 adults, 23 adolescents, 23 caregivers), and 109 completed interview 2 (66 adults, 21 adolescents, 22 caregivers).Patient participant median age was 25 (range 14-67), and 57% were female.Key treatment burden themes identified included treatment time, financial or insurance challenges, emotions and stress associated with treatments, social concerns (e.g., choosing treatments over social activities), and impact of treatments on school and work.Participants varied in how they described the extent to which treatment burden affected daily life.Strategies that participants used to manage treatment burden included prioritization of certain medications, skipping or reducing treatments, support from others, and discussions with the care team about treatments.Most participants assigned to the SIMPLIFY withdrawal arm described less treatment burden during the trial.Participant experiences with HEMT varied; some reported reduced burden from taking fewer treatments, and others described increased burden from questioning the necessity of maintenance medications.Conclusions: PwCF vary in how they conceptualize treatment burden and its impact on daily life.Participants employed numerous strategies to manage burden, and clinical stability on HEMT affects these strategies.Participants in the SIMPLIFY Trial who were randomized to withdraw a treatment described a corresponding decrease in treatment burden during the trial.Participants varied in their perceptions of treatment burden after the trial.It is important to understand how treatment burden perceptions vary among PwCF who are stable on HEMT because it may affect their decision making about other aspects of their treatment regimen.