Validation of a Novel Clinical Dyspnea Scale – A Retrospective Pilot Study

Abstract

Objective: to examine the validity of a novel dyspnea scale, Edmonton Dyspnea Inventory in idiopathic pulmonary fibrosis (IPF). Methods: Edmonton Dyspnea Inventory (EDI), is a clinical instrument to measure dyspnea severity with activities of daily living, exercise and rest using a numeric rating scale (0 -10). Consecutive IPF patients (2012-2018) with baseline MRC and EDI were included. To validate EDI, psychometric analysis was conducted. Correlations between EDI, MRC and lung function were examined. Group-based trajectory modeling was used to group patients based on dyspnea severity. Net Reclassification Improvement (NRI) was calculated to assess the improvement in 1-year mortality prediction by adding trajectory groups to MRC grade. Results: 100 consecutive IPF patients were identified; mean age 73 years (SD = 9) and 65% males; 73% were in MRC grades ≥3. Item analysis showed all 8 EDI components have excellent discrimination power with ability to differentiate patients with varying dyspnea severity. EDI has good internal consistency (Cronbach α = .92). Exploratory factor analysis showed a one-factor solution with loadings from .66 to .89 suggesting 8 EDI components measured essentially one dimension of dyspnea. All EDI components were correlated with MRC and some with lung function. Modeling data identified three EDI dyspnea severity groups with differing mortality ( P = .009). The addition of EDI dyspnea severity groups to the MRC score improved 1-year mortality prediction (NRI = .66; 95% CI, .18-1.14). Conclusions: EDI is a valid dyspnea instrument, correlated with MRC and lung function. It can categorize IPF patients into 3 dyspnea severity groups associated with increased mortality. Key Message: We describe the development of a novel scale, Edmonton Dyspnea Inventory, that facilitates measurement of dyspnea severity in the context of daily activities in patients with IPF. The results indicate that the new instrument is valid and correlated to MRC. It identifies 3 categories of severity not recognized by MRC with impact on mortality. Knowledge of dyspnea severity can help triage patients and assign appropriate therapies.