Table 4 Results of GEE regression analysis: Association of prevalence of chronic bronchitis, respiratory symptoms, and COPD with smoking at baseline and at follow up, exposure at baseline, follow-up time and exposure decline; coefficients are mutually adjusted
Chronic bronchitis a | Chronic cough | Chronic cough with phlegm production | Mild COPD b | Moderate COPD c | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
PM 10 | NO 2 | PM 10 | NO 2 | PM 10 | NO 2 | PM 10 | NO 2 | PM 10 | NO 2 | |
Sample size | 1950 | 1902 | 1922 | 342 | 342 | |||||
Parameter estimates and 95% confidence interval (times 100) | ||||||||||
Intercept | -1.51-12.04;9.02 | 4.33 *0.94;7.73 | 0.24-14.85;15.33 | 15.05 *10.15;19.95 | 5.10-6.06;16.26 | 9.07 *5.48;12.67 | -2.81-28.64;23.01 | 3.93-3.47;11.33 | -15.52 *-24.83;-6.21 | 0.15-4.04;4.34 |
Smoking at baseline | 2.42-1.31;6.16 | 1.95-1.66;5.57 | 13.94 *8.35;19.54 | 13.99 *8.36;19.62 | 5.92 *1.64;10.20 | 6.08 *1.77;10.39 | 3.92-5.34;13.19 | 4.67-4.95;14.28 | 7.02-0.89;14.92 | 7.62-1.01;16.24 |
Smokingat follow-up | -1.20 -7.45;5.06 | -1.57-7.83;4.68; | 14.59 *5.86;23.32 | 14.46 * 5.73;23.20 | 7.82 * 1.56;14.08 | 7.96 *1.83;14.09 | -9.25-27.72;9.22 | -9.45-27.38;8.48 | --2.18-16.06;11.69 | 2.04-16.02;11.93 |
Exposure at baseline d | 2.01-0.25;4.26 | 2.32 *0.18;4.47 | 4.04 *0.80;7.28 | 2.69-0.40;5.77 | 0.82-1.56;3.20 | -0.07-2.25;2.11 | 2.35-3.24;7.94 | 2.97-1.99;7.94 | 3.96 *1.60;6.32 | 2.05-0.96;5.06 |
Follow up time e | 2.22-2.24;6.69 | 1.82 *0.28;3.37 | 12.58 *5.80;19.36 | 5.37 *2.77;7.98 | 8.22 *3.07;13.37 | 3.60 *1.60;5.59 | 20.61 *7.81;33.41 | 9.12 *4.78;13.46 | 8.02 *0.01;16.03 | 2.73 *0.03;5.43 |
Follow up time exposure decline f | -0.17-4.37;4.03 | 0.21-1.08;1.50 | -8.17 *-14.54;-1.79 | -1.15-3.25;0.96 | -5.39 *-10.22;-0.57 | -0.87-2.41;0.66 | -14.62 *-25.88;-3.36 | -4.64 *-8.03;-1.26 | -6.20-13.33;0.94 | -1.66-3.8;0.048 |