Abstract
Background: The PAH-SYMPACT ® is a patient reported outcome (PRO) instrument consisting of 16 symptom and 25 impact items developed based on interviews of PAH patients and following FDA PRO guidance. Its psychometric characteristics are being evaluated using data from SYMPHONY – a phase IIIb PAH study with macitentan. The objective of the current analyses was to finalize the item content and domain structure while ensuring the PRO instrument is clinically and patient relevant. Methods: Patients enrolled in SYMPHONY completed generic and disease-specific PROs while clinicians provided assessment of severity and changes in symptomatology. Item performance, Rasch and Factor analyses of baseline data were used together with expert input to select the final items and define the domain structure. Results: The analyses included data from 278 patients (79% female, mean age 60 yrs) in WHO functional class II/III (40/59%). 41% were on background therapy with a PDE-5 inhibitor. As expected for a moderately severe population, some items had high (>50%) floor effects. Items measuring similar constructs, such as tiredness and fatigue or running errands and doing light chores, were highly correlated. Removal of redundant or mis-fitting items resulted in a final instrument with 11 symptom items (e.g. breathlessness, lack of energy) across 2 domains, and 11 impact items (e.g. walking uphill, worried) across 2 domains. Compliance in completing the questionnaire was 83%. Conclusion: PAH-SYMPACT is a clinically and PAH-patient relevant PRO instrument. It has the potential to be valuable both in clinical practice and as an outcome measure in PAH trials.
Published Version
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