| Instrument | Studies n | Convergent validity# | Longitudinal validity¶ with study details | |||
| Pearson’s correlation range | Spearman’s correlation range | Pearson’s correlation range | Type of intervention/event | Duration weeks | ||
| Disease-specific questionnaires | ||||||
| SGRQ-C | 7 | 0.69–0.82 | 0.64 | 0.63 | Exacerbation recovery | 4 |
| CCQ | 4 | NA | NA | 0.60 | Exacerbation recovery | 6 |
| 0.68–0.78 | 0.64–0.76 | 0.13 | Pulmonary rehabilitation | 8 | ||
| SGRQ | 5 | 0.72–0.74 | 0.65–0.84 | 0.36 | Pulmonary rehabilitation | 8 |
| CRQ | 5§ | -0.48– -0.33 | NA | -0.50– -0.38 | Pulmonary rehabilitation | 6–8 |
| General quality of life questionnaires | ||||||
| SF-36 (general health) | 1 | 0.58 | NA | |||
| SF-12 (physical component) | 2 | -0.60 | -0.65 | |||
| SF-12 (mental component) | 2 | -0.34 | -0.58 | |||
| SF-6D | 1 | -0.53 | NA | |||
| Clinical and physiological measures | ||||||
| mMRC | 11 | 0.29–0.61 | 0.42–0.61 | 0.20 | Pulmonary rehabilitation | 8 |
| 6MWT | 4 | -0.37– -0.27 | -0.37– -0.24 | |||
| FEV1 % predicted | 10 | -0.55– -0.17 | -0.56– -0.23 | |||
COPD: chronic obstructive pulmonary disease; SGRQ: St George’s Respiratory Questionnaire; SGRQ-C: SGRQ for COPD; CCQ: Clinical COPD Questionnaire; CRQ: Chronic Respiratory Questionnaire; SF: Short Form; mMRC: modified Medical Research Council dyspnoea scale; 6MWT: 6-min walk test; FEV1: forced expiratory volume in 1 s; NA: not applicable. #: correlation between the total CAT score and the score of another instrument that measures a similar construct. ¶: correlation between the change in total CAT score and the change in score of another instrument over time with an intervention/event. §: Jones [12], Kon [24] and Al Moamary [31] had individual CRQ domain scores correlated to the total CAT score; therefore, individual correlations of the different domains were averaged to give a total CRQ correlation to the total CAT score.