Baseline variables | Total no. (with and without respiratory symptoms) n=10 833 | No. with respiratory symptoms n=1874 | HR (95% CI)‡ |
Age (in years) | |||
≤30 | 3614 | 426 | 1.00 |
30–40 | 3777 | 633 | 1.16 (1.02 to 1.32) |
>40 | 3430 | 814 | 1.51 (1.32 to 1.72) |
Gender | |||
Male | 4648 | 977 | 1.00 |
Female | 6185 | 897 | 1.35 (1.17 to 1.56) |
Body mass index | |||
≤18 | 3709 | 612 | 1.11 (0.99 to 1.24) |
18–20.5 | 3291 | 672 | 1.00 |
>20.5 | 3562 | 548 | 1.07 (0.95 to 1.21) |
Unknown | 271 | 42 | |
Educational attainment (in years) | |||
No formal | 4754 | 977 | 1.00 |
1–6 | 3556 | 565 | 0.79 (0.71 to 0.88) |
≥6 years | 2517 | 331 | 0.67 (0.59 to 0.77) |
Baseline water arsenic concentration (μg/l) | |||
≤7 | 2300 | 333 | 1.0 |
7–40 | 2175 | 373 | 1.27 (1.09 to 1.48) |
40–90 | 2034 | 372 | 1.39 (1.19 to 1.63) |
90–178 | 2170 | 393 | 1.43 (1.23 to 1.68) |
>178 | 2154 | 403 | 1.43 (1.22 to 1.68) |
Baseline urinary arsenic concentration (μg/g creatinine) | |||
≤90 | 2110 | 306 | 1.0 |
90–160 | 2102 | 345 | 1.10 (0.94 to 1.27) |
160–246 | 2037 | 342 | 1.11 (0.95 to 1.29) |
246–406 | 2034 | 378 | 1.29 (1.11 to 1.49) |
>406 | 2039 | 420 | 1.35 (1.16 to 1.56) |
Unknown | 511 | 83 | |
Smoking status | |||
Never | 7048 | 927 | 1.0 |
Past smoker | 679 | 144 | 1.56 (1.27 to 1.92) |
Current light smoker§ | 1841 | 462 | 2.03 (1.73 to 2.37) |
Current heavy smoker | 1257 | 339 | 2.15 (1.80 to 2.58) |
Prevalent skin lesions | |||
No | 9933 | 1654 | 1.0 |
Yes | 691 | 182 | 1.09 (0.92 to 1.28) |
Unknown | 209 | 38 | |
Well switching status | |||
No | 6201 | 1121 | 1.0 |
Yes | 4099 | 726 | 0.90 (0.81 to0.99) |
Unknown | 533 | 27 |
↵* Estimated from Cox proportional hazard models.
↵† Cut-off points were determined on the quintiles of the overall study population.
↵‡ HRs for each of the variables were adjusted for all the other variables in the table except that HRs for well arsenic were not adjusted for urinary arsenic, and vice versa.
↵§ Light and heavy smokers were defined using the median value of daily cigarette consumption among current smokers.