Validity and reliability of the Japanese version of the dyspnea-12 questionnaire in patients with lung cancer

Abstract

Context: The Dyspnea-12 questionnaire is a simple tool to assess dyspnea using qualitative descriptors that include both physical and emotional domains. However, the reliability and validity of the Japanese version in patients with lung cancer have not been assessed. Objective: To determine the reliability and validity of the Japanese version of the Dyspnea-12 questionnaire in patients with lung cancer. Methods: The assessment was based on the numerical rating scale (NRS), Cancer Dyspnea Scale (CDS), and Hospital Anxiety and Depression Scale (HADS). Spearman's correlation assessed the convergent validity of Dyspnea-12 using these three scales. Exploratory factor analysis examined the construct validity. The reliability was verified using Cronbach's alpha. Anxiety, depression, clinical dyspnea, presence of chronic obstructive pulmonary disease (COPD), and patient status were identified by discriminating performance. Results: The analysis included 113 patients with lung cancer. A significant positive correlation was found between Dyspnea-12 and NRS, CDS, and HADS scores. Similar to the original version, factor analysis clearly classified Dyspnea-12 into two components (physical and emotional), thereby confirming its construct validity. Cronbach's alpha values for the total Dyspnea-12 and its physical and emotional components were 0.97, 0.95, and 0.96, respectively. Patients with anxiety, depression, and clinical dyspnea and those in the palliative phase had significantly higher Dyspnea-12 scores than their respective counterparts. The Dyspnea-12 scores of patients with and without COPD were similar. Conclusion: The Japanese version of the Dyspnea-12 questionnaire is a useful and reliable tool to assess the multi-dimensional aspects of dyspnea in patients with lung cancer.