Comparison between tools for measuring breathlessness: cross-sectional observation and predictive properties

Abstract

Background: Dyspnoea is one of the most important symptoms of chronic obstructive pulmonary disease (COPD), but it’s not easy to measure this perception. The Baseline Dyspnea Index (BDI), the Dyspnoea-12 (D-12) and the Activity component of the St. George’s Respiratory Questionnaire (SGRQ) were all recognized as tools for measuring dyspnea.

Aim: To directly compare the measuring properties of tools in patients with COPD.

Methods: One hundred and twenty-two outpatients with stable COPD were recruited (74.5 ± 6.4 years) and completed the questionnaires of the BDI, D-12 and SGRQ Activity as well as spirometry. The survival status, episodes of acute exacerbation of COPD (AECOPD) and hospital admission due to AECOPD were recorded.

Results: The scores of the BDI, D-12 and SGRQ Activity showed moderate correlations with each other (│Rs│= 0.53 to 0.66). FEV₁ is weakly or moderately associated with the BDI (Rs = 0.40), D-12 (Rs = 0.30) and SGRQ Activity (Rs = 0.42). Eighteen patients (14.8%) have died and AECOPD events were identified in 66 out of 117 available subjects (56.4%). Forty-one patients out of 119 available subjects (34.5%) have been admitted to hospital due to AECOPD at least once during the follow-up period. In univariate cox proportional analysis, the scores of the BDI, D-12 and SGRQ Activity all could predict the events of AECOPD and hospital admission. But the scores of D-12 could not predict mortality, while those of the BDI and SGRQ Activity could.

Conclusions: The BDI, D-12 and SGRQ Activity showed moderate, not strong correlations with each other in patients with COPD.