Development and Initial Validation Analyses of the Living with Idiopathic Pulmonary Fibrosis (L-IPF) Questionnaire.

RATIONALE Several new drugs for idiopathic pulmonary fibrosis (IPF) are in development. Tools are needed to assess whether these drugs benefit patients on outcomes that matter most to them. Health-related quality of life (HRQL) is one such outcome. It is influenced by many factors, but symptoms and their impacts are two strong drivers. OBJECTIVES To develop a questionnaire to assess symptoms, disease impacts and HRQL specifically for patients with IPF. METHODS Working with the U.S. Food and Drug Administration through the Drug Development Tool Qualification process, focus groups, concept elicitation and cognitive debriefing interviews were conducted to inform the development of a 44-item pilot questionnaire. The pilot paper-and-pen questionnaire was migrated to an equivalent electronic version and field tested in a 14-day study. Response data were subjected to psychometric testing, including exploratory factor analysis, item calibration using item response theory models, test-retest reliability, and validity testing. MEASUREMENTS AND MAIN RESULTS 125 patients with IPF (62.4% men) completed the longitudinal study. The mean (±SD) age of the cohort was 69±7.60 years, and the mean percent predicted forced vital capacity (FVC%) was 71%±20.0. After factor and item analyses, 35 items were retained, and these comprise the two modules (Symptoms and Impacts) of the Living with IPF (L-IPF) questionnaire. The L-IPF yields five scales demonstrating good psychometric properties, including correlation with concurrently-collected FVC% and the ability to discriminate between patients with differing levels of IPF severity. CONCLUSIONS The L-IPF is a new questionnaire that assesses symptoms, disease impacts and HRQL in patients with IPF.