Cough-specific Quality of Life Predicts Disease Progression Among Patients with Interstitial Lung Disease: Data from the Pulmonary Fibrosis Foundation Patient Registry.

Overview

abstract

BACKGROUND: Cough is a common symptom of interstitial lung disease (ILD) and negatively impacts health-related quality of life (QOL). Previous studies have shown that among patients with idiopathic pulmonary fibrosis, cough may predict progression of lung disease and perhaps even respiratory hospitalizations and mortality. RESEARCH QUESTION: Does cough-specific QOL predict disease progression, respiratory hospitalization, lung transplantation, and death among patients with ILD? STUDY DESIGN AND METHODS: We analyzed data from the Pulmonary Fibrosis Foundation Registry, which is comprised of a multi-center population of well-characterized patients with interstitial lung disease. We first examined associations between patient factors and baseline scores on the Leicester cough questionnaire (LCQ), a cough-specific QOL tool, utilizing a proportional odds model. Next, we examined associations between baseline LCQ scores and patient-centered clinical outcomes as well as pulmonary function parameters, utilizing a univariable and multivariable proportional hazards model that was adjusted for clinically relevant variables, including measures of disease severity. RESULTS: 1,447 patients with ILD were included in our study. In our multivariable proportional odds model, we found that the following patient factors were associated with worse cough-specific QOL: younger age, diagnosis of "other ILD", gastroesophageal reflux disease, and lower % predicted forced vital capacity. Multivariable Cox regression models, adjusting for several variables, including baseline disease severity, showed that a one-point decrease in LCQ score (indicating lower cough-specific QOL) was associated with a 6.5% higher risk of respiratory-related hospitalization (hazard ratio [HR], 1.065 [95% confidence interval (CI), 1.025-1.107]), a 7.4% higher risk of death (HR, 1.074 [95% CI, 1.020-1.130]), and an 8.7% higher risk of lung transplant (HR, 1.087 [95% CI 1.022-1.156]). INTERPRETATION: Among a large population of well-characterized patients with interstitial lung disease, cough-specific QOL was independently associated with respiratory hospitalization, death, and lung transplantation.