Table 1 Baseline participant characteristics.
From: Association between nitrogen dioxide and incident breast cancer in Alberta’s tomorrow project
Variables | Overall | Cases | Non-cases | P | ||||
|---|---|---|---|---|---|---|---|---|
N or mean | % or SD | N or mean | % or SD | N or mean | % or SD | |||
Number of participants | 15,536 | 100% | 523 | 3.40% | 15,013 | 96.60% | ||
Follow-up time (years) | 12.6 | 4.2 | 7.9 | 4.9 | 12.8 | 4.1 | ||
Age at baseline | 53.5 | 9.6 | 56.9 | 8.7 | 53.4 | 9.6 | < 0.05 | |
Alcohol consumption | Never | 1127 | 7.7 | 39 | 7.8 | 1088 | 7.6 | 0.6 |
Less than once per month | 2964 | 20.1 | 107 | 21.4 | 2857 | 20.1 | ||
1–3 times per month | 3652 | 24.8 | 114 | 22.8 | 3538 | 24.9 | ||
Once per week | 1623 | 11 | 47 | 9.4 | 1576 | 11 | ||
2–5 times per week | 4229 | 28.7 | 151 | 30.1 | 4078 | 28.7 | ||
More than 6 times per week | 1132 | 7.7 | 43 | 8.5 | 1089 | 7.7 | ||
Unknown/Missing | 809 | 5.2 | 22 | 4.2 | 787 | 5.2 | ||
Birth | Two or less | 4334 | 32.3 | 146 | 32.7 | 4188 | 32.3 | 0.19 |
3–4 | 7893 | 58.8 | 261 | 58.4 | 7632 | 58.8 | ||
Greater than 4 | 1196 | 8.9 | 40 | 8.9 | 1156 | 8.9 | ||
Unknown/Missing | 2113 | 13.6 | 76 | 14.5 | 2037 | 13.6 | ||
Race | White | 10,140 | 94.9 | 312 | 59.7 | 9828 | 94.9 | 0.002 |
Other | 540 | 5.1 | 12 | 2.3 | 528 | 5.1 | ||
Unknown/Missing | 4856 | 31.3 | 199 | 38 | 4657 | 31 | ||
Education | High school or below | 3697 | 23.8 | 131 | 25.1 | 3566 | 23.8 | 0.2 |
Diploma or trade | 5565 | 35.8 | 198 | 37.9 | 5367 | 35.8 | ||
University-level education | 6266 | 40.4 | 193 | 37 | 6073 | 40.4 | ||
Unknown/Missing | -- | -- | -- | -- | -- | -- | ||
Contraceptive use | Ever | 13,825 | 89 | 467 | 89.3 | 13,358 | 89 | 0.87 |
Never | 1704 | 11 | 56 | 10.7 | 1648 | 11 | ||
Unknown/Missing | -- | -- | -- | -- | -- | -- | ||
Deprivation score - social | Q1 (least deprived) | 2698 | 18.2 | 92 | 18.9 | 2606 | 18.2 | 0.25 |
Q2 | 2809 | 19 | 97 | 19.9 | 2712 | 19 | ||
Q3 | 2956 | 20 | 95 | 19.5 | 2861 | 20 | ||
Q4 | 3337 | 22.6 | 115 | 23.6 | 3222 | 22.5 | ||
Q5 (most deprived) | 2985 | 20.2 | 88 | 18.1 | 2897 | 20.3 | ||
Unknown/Missing | 751 | 4.8 | 36 | 6.9 | 715 | 4.8 | ||
Deprivation score – material | Q1(least deprived) | 4321 | 29.2 | 133 | 27.3 | 4188 | 29.3 | 0.31 |
Q2 | 3572 | 24.2 | 124 | 25.5 | 3448 | 24.1 | ||
Q3 | 2832 | 19.2 | 95 | 19.5 | 2737 | 19.1 | ||
Q4 | 2510 | 16.9 | 83 | 17 | 2427 | 17 | ||
Q5 (most deprived) | 1550 | 10.5 | 52 | 10.7 | 1498 | 10.5 | ||
Unknown/Missing | 751 | 4.8 | 36 | 6.9 | 715 | 4.8 | ||
Fruit consumption, servings/day | Zero | 578 | 3.7 | 21 | 4 | 557 | 3.7 | 0.6 |
One | 3137 | 20.3 | 95 | 18.2 | 3042 | 20.4 | ||
Two | 5107 | 33 | 190 | 36.4 | 4917 | 32.9 | ||
Three | 3606 | 23.3 | 121 | 23.2 | 3485 | 23.3 | ||
Four | 1915 | 12.4 | 58 | 11.1 | 1857 | 12.4 | ||
Five or more | 1119 | 7.3 | 37 | 7.1 | 1082 | 7.3 | ||
Unknown/Missing | -- | -- | -- | -- | -- | -- | ||
Vegetable consumption, servings/day | Zero | -- | -- | -- | -- | -- | -- | 0.33 |
One | 1862 | 12.1 | 74 | 14.2 | 1788 | 12 | ||
Two | 4210 | 27.2 | 128 | 24.6 | 4082 | 27.3 | ||
Three | 3918 | 25.4 | 141 | 27.1 | 3777 | 25.3 | ||
Four | 2842 | 18.4 | 95 | 18.2 | 2747 | 18.4 | ||
Five or more | 2450 | 15.8 | 81 | 15.5 | 2369 | 15.9 | ||
Unknown/Missing | -- | -- | -- | -- | -- | -- | ||
Income | Less than 50,000 | 3046 | 21.2 | 123 | 25.5 | 2923 | 21.1 | 0.09 |
$50,000-$100,000 | 4889 | 34.1 | 169 | 35 | 4720 | 34 | ||
$100,000-$150,000 | 3125 | 21.8 | 99 | 20.5 | 3026 | 21.8 | ||
Greater than $150,000 | 3290 | 22.9 | 92 | 19 | 3198 | 23.1 | ||
Unknown/Missing | 1186 | 7.6 | 40 | 7.6 | 1146 | 7.6 | ||
Maternal history of breast cancer | Yes | 4023 | 41.1 | 171 | 46.7 | 3852 | 41 | < 0.05 |
No | 5759 | 58.9 | 195 | 53.3 | 5564 | 59 | ||
Unknown/Missing | 5754 | 37 | 157 | 30 | 5597 | 37.3 | ||
Physical activity | Met | 514 | 10.8 | 15 | 12.6 | 499 | 10.7 | < 0.05 |
Not Met | 4263 | 89.2 | 104 | 87.4 | 4159 | 89.3 | ||
Unknown/Missing | 10,759 | 69.3 | 404 | 77.2 | 10,355 | 69 | ||
Smoking | Never | 7674 | 87.2 | 279 | 89.1 | 7395 | 87.2 | 0.14 |
Occasionally | -- | -- | -- | -- | -- | -- | ||
Daily | 870 | 9.9 | 30 | 9.6 | 840 | 9.9 | ||
Unknown/Missing | 6738 | 43.4 | 210 | 40.2 | 6528 | 43.5 | ||
BMI | Underweight | -- | -- | -- | -- | -- | -- | < 0.05 |
Healthy | 5969 | 41.6 | 168 | 36.2 | 5801 | 41.8 | ||
Overweight | 4697 | 32.7 | 152 | 32.7 | 4545 | 32.7 | ||
Obese | 3523 | 24.6 | 142 | 30.5 | 3381 | 24.4 | ||
Unknown/Missing | 1188 | 7.6 | 58 | 11.1 | 1130 | 7.5 | ||
