Cigarette and Waterpipe Smoking Decrease Respiratory Quality of Life in Adults: Results from a National Cross-Sectional Study
Table 2
Factorial analysis of the Clinical COPD Questionnaire.
Items
Factor loading
Factors correlation*
Correlation with FEV1/FVC*
Factor 1**
Factor 1
−0.436
Had dyspnea at rest
0.480
0.771
−0.356
Had dyspnea on effort
0.607
0.876
−0.422
Was unable to do strenuous effort such as going up stairs
0.701
0.871
−0.451
Was unable to do moderate effort such as walking
0.776
0.896
−0.430
Was anxious about breathing difficulties or getting a cold
0.671
0.786
−0.340
Was depressed because of respiratory problems
0.715
0.733
−0.227
Was unable to socialize (talking, visiting, …)
0.949
0.767
−0.291
Was unable to do daily activities/dressing …
0.925
0.819
−0.313
Factor 2**
Factor 2
−0.442
Had sputum production
0.980
0.959
−0.414
Had cough
0.937
0.956
−0.439
Total scale
−0.464
*All correlations were significant (P < 0.001); factor 1 correlation with CCQ was 0.980; factor 2 correlation with CCQ was 0.829; **Cronbach’s alpha = 0.910 for the full scale, 0.909 for factor 1 and 0.859 for factor 2; factor 1 correlation coefficient with factor 2 was 0.700.
