Table 2 Asthma incidence and results from Cox regression analysis by baseline socio-demographic and health behavior characteristics
Person-years of follow-up | Number of asthma cases | Incidence per 1000 person-years (95% CI) | Crude HR (95% CI) | Adjusted HR* (95% CI) | |
|---|---|---|---|---|---|
Sex | |||||
Male | 10,766,510 | 70,770 | 6.6 (4.5-9.8) | 1.00 | 1.00 |
Female | 10,508,380 | 138,290 | 13.2 (9.7-18.2) | 1.99 (1.23-3.23)† | 2.13 (1.26-3.62) |
Age group | |||||
12-13 | 6,007,840 | 53,130 | 8.8 (5.6-14.7) | 1.00 | 1.00 |
14-15 | 6,044,580 | 56,290 | 9.3 (6.0-15.1) | 1.03 (0.53-2.00) | 1.09 (0.55-2.16) |
16-18 | 9,222,480 | 99,640 | 10.8 (7.6-15.8) | 1.18 (0.65-2.16) | 1.16 (0.63-2.16) |
Area of residence | |||||
Urban | 17,056,720 | 182,260 | 10.7 (8.3-14.0) | 1.00 | 1.00 |
Rural | 4,218,170 | 26,810 | 6.4 (3.4-13.2) | 0.61 (0.27-1.35) | 0.58 (0.25-1.35) |
Income | |||||
High | 3,363,690 | 37,290 | 11.1 (6.4-20.9) | 1.00 | 1.00 |
Middle | 14,358,250 | 123,840 | 8.6 (6.5-11.7) | 0.78 (0.40-1.54) | 0.72 (0.36-1.44) |
Low | 3,552,950 | 47,940 | 13.5 (7.6-26.2) | 1.19 (0.53-2.69) | 1.13 (0.48-2.66) |
BMI status | |||||
Normal | 16,839,660 | 174,930 | 10.4 (8.0-13.7) | 1.00 | 1.00 |
Overweight or obese | 4,435,230 | 34,130 | 7.7 (4.6-14.3) | 0.76 (0.39-1.45) | 0.73 (0.37-1.46) |
Passive smoking exposure | |||||
Absent | 12,860,340 | 93,130 | 7.2 (5.0-11.0) | 1.00 | 1.00 |
Present | 8,414,550 | 115,930 | 13.8 (10.2-18.9) | 1.88 (1.19-2.98)† | 2.06 (1.27-3.34) |
Personal smoking | |||||
Never/Former | 17,730,630 | 75,530 | 9.9 (7.6-13.1) | 1.00 | 1.00 |
Occasionally/Daily | 3,544,260 | 33,530 | 9.5 (5.4-17.7) | 0.95 (0.48-1.87) | 0.67 (0.34-1.30) |
Physical exercise | |||||
Inactive | 18,263,280 | 175,820 | 9.6 (7.4-12.7) | 1.00 | 1.00 |
Active | 3,011,620 | 33,250 | 11.0 (6.2-21.1) | 1.13 (0.55-2.35) | 1.27 (0.57-2.83) |