Table I.
Descriptive characteristics of bronchitis cases and controls
| Bronchitis Cases | Controls | p value | |
|---|---|---|---|
| (N=4 873) | (N =9 746) | ||
| Mean age in years* | 40.2 | 40.8 | 0.94 |
| Range | 16 – 69 | 17 – 69 | |
| Educational Level | < 0.0001 | ||
| Elementary/Less | 1 479 (30.4%) | 3 248 (33.3%) | |
| Middle School | 1 374 (28.2%) | 2 859 (29.3%) | |
| High School | 1 265 (26.0%) | 2 290 (23.5%) | |
| College and more | 745 (15.5%) | 1 351 (13.9%) | |
| Total Family Income in Last Year (yuans) | 0.87 | ||
| <10,000 | 936 (19.2%) | 1 787 (18.3%) | |
| 10,000 – 19,999 | 1 809 (37.1%) | 3 741 (38.4%) | |
| 20,000 – 29,999 | 1 257 (25.8%) | 2 552 (26.2%) | |
| >30,000 | 870 (18.9%) | 1 665 (17.1%) | |
| Ever smoking | 174 (3.6%) | 197 (2.02%) | < 0.0001 |
| Ever exposed to second hand tobacco smoke | 3 405 (69.9%) | 6 635 (68.1%) | 0.43 |
| Mean Number of Jobs | 1.66 | 1.55 | < 0.0001 |
| Range | 0.0 – 6.0 | 0.0 – 6.0 |
*
Age at diagnosis for cases and cutoff year for controls