Objective To correlate functional capacity test scores from chronic obstructive pulmonary disease (COPD) subjects with their functional state as assessed by health-related quality of life questionnaires (one respiratory disease-specific [SGRQ] and one generic [SF-36] questionnaire). Materials and methods Study of a case series of 8 COPD patients. The following tests were performed: 1) Six-minute walk test (6-MWT); 2) Shuttle walking test (SWT); 3) Six-minute step test (6-MST); 4) Two-minute sit-to-stand test (STST); and 5) Pegboard and ring test (PBRT). Besides these tests, two health-related quality of life questionnaires were administered: The St George's Respiratory Questionnaire (SGRQ) and the Short Form 36 (SF-36) health survey questionnaire. The statistical analysis was carried out by using the Shapiro-Wilk normality test, while correlations were assessed using Pearson's (parametric data) or Spearman's (non-parametric data) rank tests, with p < 0.05. Results The 6-MWT showed strong correlation with the SF-36 scales of physical functioning, general health, vitality, social functioning and mental health. Conversely, the other functional capacity tests showed no correlation with this questionnaire. The SGRQ showed no correlation with any of the tests. Conclusions The 6-MWT may be a good test to reflect the health-related quality of life of COPD subjects.
Determining minimally important changes in generic and disease-specific health-related quality of life questionnaires in clinical trials of rheumatoid arthritis