Terms used in this evidence summary
Baseline Dyspnoea Index (BDI): a validated 24-item questionnaire to rate the severity of dyspnoea at a single time point. It is administered by an investigator and measures 3 components relating to dyspnoea in activities of daily living (functional impairment, magnitude of task and magnitude of effort). Each category is rated on a 5-point scale ranging from 0 (very severe) to 4 (no impairment) giving a total score ranging from 0 to 12, with a lower score indicating more severe dyspnoea.
St George's Respiratory Questionnaire (SGRQ): a validated 50-item questionnaire developed to measure health status (quality of life) in people with diseases of airways obstruction such as COPD. It is self-administered and scores are subsequently calculated for 3 domains (symptoms, activity and psychosocial impact) as well as a total score. A score of 100 represents worst possible health status and 0 indicates best possible health status. A minimum change in score of 4 units is considered to be clinically important.
Transition Dyspnoea Index (TDI): measures changes in dyspnoea severity from the baseline as established by the BDI. The 3 components (functional impairment, magnitude of task and magnitude of effort) are each rated on a 7-point scale ranging from −3 (major deterioration) to +3 (major improvement), giving a total score from −9 to +9, with a lower score indicating more deterioration in dyspnoea. A TDI focal score of ≥1 is considered to be clinically important.