Table 2. Correlation between sleep quality, anxiety, depression and health-related quality of life at baseline.
| r-value | PSQI | CAT | HADS-A | HADS-D | ISWT |
|---|---|---|---|---|---|
| PSQI (n) | 1 (61) | 0.523a (60) | 0.461a (57) | 0.410a (57) | −0.161 (48) |
| CAT (n) | 0.523a (60) | 1 (60) | 0.429a (57) | 0.300b (57) | −0.401a (48) |
| HAD-A (n) | 0.461a (57) | 0.429a (60) | 1 (57) | 0.609a (57) | −0.128 (48) |
| HAD-D (n) | 0.410a (57) | 0.300b (57) | 0.609a (57) | 1 (57) | −0.346b (48) |
| ISWT (n) | −0.161 (48) | −0.401a (48) | −0.128 (48) | −0.346b (48) | 1 (48) |
Abbreviations: CAT=COPD assessment test; HADS-A, Hospital Anxiety and Depression Scale—anxiety score; HADS-D, Hospital Anxiety and Depression Scale—depression score; ISWT, incremental shuttle walk test; n, number in group; PSQI=Pittsburgh Sleep Quality Index at baseline.
a
Correlation is significant at the 0.01 level (2-tailed).
b
Correlation is significant at the 0.05 level (2-tailed).