(158) Validation of the Q-Life app: an individualized patient-reported outcome measure to assess quality of life

Background: Quality of life and prognosis of people with Cystic Fibrosis (pwCF) are drastically changing since the arrival of Cystic Fibrosis Transmembrane conductance Regulator (CFTR) modulators. Nevertheless, the variable impact of new therapies on individual lives can be difficult to capture with standard questionnaires or physical outcome measures.
Objective: To enable a systematical assessment of the impact of care and treatment on important and relevant personal factors of quality of life, we developed and validated the Q-Life app as an individualized patient-reported outcome measure (PROM) in pwCF.

Methods: The Q-Life app was developed in collaboration with pwCF and parents of children with CF. In the app, pwCF can describe and rank 3-5 factors they find important for their personal quality of life. Factors can be labelled with an appropriate category and scored to what extent the individual feels limited by CF on a 5-point Likert scale, ranging from not limited to almost fully limited. Overall Q-Life score was calculated as percentage of the highest possible total score. An instruction video is available at https://youtu.be/3dNTdeI2TYE.

In a cross-sectional study in pwCF ≥14 years, internal consistency and test-retest reliability of Q-Life scores were assessed. In addition, construct validity was evaluated by associations with Cystic Fibrosis Questionnaire-Revised (CFQ-R) scores and percent predicted forced expiratory volume in 1s (ppFEV1). Moreover, we analyzed differences between groups with and without pulmonary exacerbations requiring intravenous (IV) antibiotics and between adolescents ≤18 years and adults >18 years. Sensitivity to change is currently assessed in a cohort of pwCF who initiated elexacaftor/tezacaftor/ivacaftor.

Results: In total, 89 pwCF (median age 24 years (IQR: 17 years), 49% female) were enrolled. Altogether, participants described 340 individual Q-Life factors, which were most frequently labelled with the categories: social activities (19%), physical exercise and sport (16%), work and education (13%), relaxation and rest (9%) and pulmonary symptoms (8%). Reliability of Q-Life scores was demonstrated by high internal consistency (Cronbach’s α=0.80) and test-retest reliability (intraclass correlation coefficient=0.90, p< 0.001). Q-Life scores were also correlated with overall CFQ-R scores (rs=0.58, p< 0.001), CFQ-R respiratory domain scores (rs=0.39, p< 0.001) and ppFEV1 (rs=0.58, p< 0.001), supporting construct validity. Furthermore, higher Q-Life scores reflected a better quality of life in pwCF without IV-treated pulmonary exacerbations in the last 12 months compared to pwCF with at least 1 IV-treated pulmonary exacerbation (median: 85.00% (IQR: 27.71%) vs. 67.71% (IQR: 28.75%), p< 0.001). Q-Life scores were also higher in adolescents compared to adults (median: 91.67% (IQR: 33.75%) vs. 75.00% (IQR: 26.67%), p=0.011).

Conclusions: Validation of the Q-Life app as individualized PROM was supported by a high internal consistency, test-retest reliability and construct validity of Q-Life scores.

Acknowledgements: This work was supported by the Dutch Cystic Fibrosis Foundation [CFOS 2019 and 2020] and Health~Holland [TKI-LSH PPP allowance 2019]

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