Brazilian version of the Clinical COPD Questionnaire, administered by interview: reliability and validity measurement properties.

OBJECTIVE

To test the reliability, validity, and interpretability of the Brazilian version of the Clinical COPD Questionnaire (CCQ) in patients with COPD.

METHODS

Fifty patients with COPD completed the CCQ by interview on two occasions. At the first visit, the CCQ was administered twice, by two different raters, approximately 10 min apart; the patients also underwent spirometry and were administered the COPD Assessment Test, the modified Medical Research Council scale, and Saint George's Respiratory Questionnaire (SGRQ). At the second visit (1-2 weeks later), the CCQ was readministered. We tested the hypothesis that the CCQ total score would correlate positively with the total and domain SGRQ scores (r ≥ 0.5).

RESULTS

Of the 50 patients, 30 (60%) were male. The mean age was 66 ± 8 years, and the mean FEV1 was 44.7 ± 17.9% of the predicted value. For all CCQ items, Cronbach's alpha coefficient (95% CI) was 0.93 (0.91-0.96). To analyze the interrater reliability and test-retest reliability of the CCQ, we calculated the two-way mixed effects model/single measure type intraclass correlation coefficient (0.97 [95% CI: 0.95-0.98] and 0.92 [95% CI: 0.86-0.95], respectively); the agreement standard error of measurement (0.65 for both); the smallest detectable change at the individual level (1.81 and 1.80, respectively) and group level (0.26 and 0.25, respectively); and the limits of agreement (-0.58 to 0.82 and -1.14 to 1.33, respectively). The CCQ total score correlated positively with all SGRQ scores (r ≥ 0.70 for all).

CONCLUSIONS

The Brazilian version of the CCQ showed an indeterminate measurement error, as well as satisfactory interrater/test-retest reliability and construct validity.