Patient-Reported Outcome Scale for Idiopathic Pulmonary Fibrosis: Development and Validation in China.

Purpose: To develop and validate the patient-reported outcome scale for idiopathic pulmonary fibrosis (IPF-PRO) to provide a reliable and scientific measure for clinical trials on idiopathic pulmonary fibrosis (IPF).

Methods: We analyzed the relevant literature and medical records and conducted interviews and panel discussions to develop the conceptual framework and generate the item pool. We subjected the collected items to removal, mergence, or modification to form the initial scale through a qualitative review by experts and patients. Subsequently, we conducted two field surveys to select items for the final scale based on the classical test theory and item response theory (IRT). Finally, we conducted a formal survey to assess the measurement properties of the IPF-PRO.

Results: The IPF-PRO included 18 items across four domains, namely physiology, psychology, environment, and satisfaction. The Cronbach's α coefficient and generalized coefficient of the IPF-PRO were 0.917 and 0.931, respectively. The content validity, structural validity, criterion validity, and discriminant validity all met relevant standards. The results of the item analysis based on IRT were considered acceptable. The ordinal logistic regression analysis findings showed that all items' p values were greater than 0.01 when the domain scores matched variables. The IPF-PRO response and completion rates were both 100%. The median completion time was 7 min [IRQ = 3.7 min (Q3 = 9.0 min, Q1 = 5.3 min)].

Conclusion: The 18-item IPF-PRO developed in this study has demonstrated good reliability and validity, indicating that it is a reliable and scientific measure for IPF clinical trials.