Reliability and validity of Thai version of Baseline Dyspnea Index (BDI) and Transitional Dyspnea Index (TDI) in patients with COPD

<bold>Background:</bold> Dyspnea is a dominant symptom experienced by patients with COPD. Measuring the dyspnea perception is important to evaluate the effectiveness of the interventions, indicate disease severity, and detect disease progression. BDI and TDI were designed to evaluate the impact of daily activities on patients’ dyspnea at a single state and changes from the baseline respectively. <bold>Aim:</bold> To assess the reliability and validity of the Thai version of TDI/BDI. <bold>Methods:</bold> 31 patients with COPD (4 women; age 72±6yr; FEV1/FVC% 52±10) were included. The BDI/TDI were rated by 2 raters, 1 hour apart, at the baseline and follow-up visit, respectively. Then BDI/TDI were rated again by phone interview on the next day of each visit. <bold>Results:</bold> Baseline BDI=8.5±2.9, mMRC=1(0.8,2), CAT=7.1±5.6; Follow-up TDI=1.6±2.6, mMRC=1(1,2), CAT=6.5±5.4. Internal consistency by Cronbach’s alpha of the Thai version of BDI/TDI were 0.90 and 0.92, respectively. Test-retest reliability of BDI were ICC=0.87, 080, 0.82 while for TDI were ICC=0.82, 0.83, 0.57. Inter-rater reliability by Kappa were 0.29, 0.78, 0.47 for BDI and 0.57, 0.61, 0.48 for TDI. There were no correlations between BDI and TDI with 6 min walk distance (p>0.05). There was a significant negative correlation between BDI and mMRC (r=-0.57, p=0.002) and CAT (r=-0.70, p<0.0001). There were no correlations between TDI with changes in mMRC and CAT (p>0.05). <bold>Conclusion:</bold> The Thai version of BDI/TDI showed excellent internal consistency reliability and moderate to good test-retest reliability. The inter-rater reliability showed slight to moderate agreement. Only BDI has a moderate to strong negative association with mMRC and CAT.