Table 1

Time points and descriptions for HRQoL and exercise capacity assessments

MeasureResearch toolDescription of research toolTime
0 months6 months12 months
Quality of lifeCRQThe 20-item self-administered disease specific questionnaire measures the impact of COPD on a person’s HRQoL across four domains: dyspnoea (individualised domain), fatigue, emotional function and mastery.14 Participants respond on a 7-point scale ranging from 1 (maximum impairment) to 7 (no impairment). The MCID is a change of 0.5 points per item or a change in the total CRQ score of 10 points between measurement time points.19
CATThis disease-specific questionnaire provides a measure of health status and is responsive to change with treatment and exacerbations.15 20 It comprises eight questions relating to respiratory symptoms, exercise tolerance, performance of activities of daily living, confidence in leaving the home, sleep and energy levels. Each question scored on a 6-point scale (0 to 5). The MCID is two points.20
Functional exercise capacity6MWTMeasures the maximum distance (6MWD) an individual covers over 6 min, irrespective of any rests taken. The MCID is 30 m.16
  • The CRQ, CAT and 6MWT are widely used in COPD studies and are responsive to interventions; their reliability and validity have been reported previously.16 20 21

  • CAT, COPD assessment test; CRQ, Chronic Respiratory Disease Questionnaire; HRQoL, health-related quality of life; MCID, minimum clinically important difference; 6MWD, 6 min walk distance; 6MWT, 6 min walk test.