Patient-reported outcomes in idiopathic pulmonary fibrosis; validity and reliability of visual analogue scales

Introduction: Patient-reported outcome measures (PROMs) are increasingly used to evaluate disease burden in idiopathic pulmonary fibrosis (IPF) clinical trials, but are too lengthy for use in daily practice. There is a need for feasible, reliable tools for trials and daily practice. We aimed to evaluate the validity and reliability of simple online visual analogue scales (VAS). Methods: Patients with IPF completed weekly online VAS on dyspnea, fatigue, cough and general wellbeing for 24 weeks using an app. K-BILD questionnaire was completed at week 0, 12 and 24. Pearson correlation was used to calculate correlations between VAS and K-BILD scores. Reliability over time was assessed using the coefficient of variation. Results: 83 patients completed PROMs (mean age 71, 91% male). VAS fatigue, dyspnea and general wellbeing had a moderate to strong significant correlation with K-BILD total and breathlessness domain score at all timepoints (table 1). In 41 clinically stable patients, within-patient variability of different VAS scores during 12 weeks was low: fatigue 4.5%, dyspnea 5.0%, general wellbeing 5.9%, cough 7.3%. Conclusion: VAS scores significantly correlate with K-BILD scores and are consistent over time in clinically stable patients with IPF. Because of their simplicity, visual analogue scales have the potential to be used for systematic evaluation of disease course in trials and daily practice.