Rationale: Dyspnea is the cardinal symptom in patients with any type of interstitial lung disease (ILD); however, there are limited data on dyspnea among patients with connective tissue disease-related ILD (i.e., CTD-ILD).
Objectives: To explore the utility of two dyspnea instruments (the University of California San Diego Shortness of Breath Questionnaire [UCSD] and the Dyspnea-12 [D-12]) and use their scores to examine the impact of dyspnea on the lives of patients with CTD-ILD.
Methods: Subjects were enrolled from the Autoimmune Lung Database (ALD) at National Jewish Health. Chronbach's alpha was used to assess the internal consistency reliability of the two dyspnea questionnaires. We used the Multi-Dimensional Health Assessment Questionnaire [MDHAQ] as a measure of health status and examined associations between health status and dyspnea by using Pearson product-moment correlation and linear regression.
Results: The internal consistency reliability of each of the two dyspnea questionnaires was excellent (alpha=0.9 for each). There were significant correlations between either of the two dyspnea measures and MDHAQ components. While controlling for ILD severity, dyspnea as assessed by the UCSD, was a significant predictor of physical function (p=0.04), psychological well-being (p=0.005), and fatigue (p=0.02); dyspnea as assessed the D-12, was a significant predictor of psychological well-being (p=0.01) and global status (p=0.03).
Conclusion: Dyspnea significantly affects day-to-day functioning and global well-being in patients with CTD-ILD. The UCSD and D-12 yield meaningful information about these patients that measures of pulmonary physiology cannot. Future studies should examine other performance characteristics of these self-report measures in patients with CTD-ILD.