CF Tummy Tracker: A Cystic Fibrosis-Specific Patient Reported Outcome Measure for Daily Gastrointestinal Symptom Burden

Objective To develop a cystic fibrosis (CF) specific patient-reported outcome measure (PROM) to measure the daily burden of gastrointestinal symptoms for people with CF (pwCF) aged 12 and over and address the lack of validated outcome measures for gastrointestinal symptoms in CF. Patients and methods CF Tummy Tracker was developed through a 5-stage approach in accordance with regulatory guidance. This included development and refinement of a conceptual framework; item generation; refinement; reduction; selection; and initial PROM testing. A mixed-methods approach was used consisting of expert panel discussions, a focus group, interviews and an online survey. In initial testing, participants completed the PROM daily for 14 days via a smartphone app. Study dates 14/03/2022 – 03/12/2023. Results The CF community were involved throughout its development via a focus group (n=7 pwCF), interviews (n=11 pwCF) and an online survey (n=180 pwCF). A formative model was confirmed for the PROM. The final PROM, CF Tummy Tracker, consists of 10 items capturing gastrointestinal symptom burden, tested in 151 pwCF. The PROM demonstrated no floor or ceiling effects, high test-retest reliability (ICC=0.94) and strong correlation with the anchor question. Conclusion CF Tummy Tracker aims to address the gap in validated CF-specific PROMs for daily completion. Further testing of the psychometric properties of the PROM are planned in a new patient cohort to validate its use in clinical trials and support its use in both electronic and paper formats to increase accessibility.