TABLE 3.
Occupational and Household Activity, Transportation Activity, and Sedentary Behavior in Relation to Invasive Breast Cancer Incidence Among Postmenopausal Women: National Institutes of Health–AARP Diet and Health Study, 1996–2003
| No. Person-Years | No. Cases | Age-Adjusted RR (95% CI) | Ptrend | Multivariate 1 RR (95% CI)a | Ptrend | Multivariate 2 RR (95% CI)b | Ptrend | |
| Occupational and Household Activity | ||||||||
| Routine activity during the day | .003 | .024 | .092 | |||||
| Sitting all day | 49 144 | 258 | 1.00 | 1.00 | 1.00 | |||
| Sitting and a little walking | 206 859 | 933 | 0.84 (0.73, 0.96) | 0.84 (0.73, 0.97) | 0.86 (0.75, 0.99) | |||
| Standing or walking, no lifting | 251 087 | 1132 | 0.81 (0.71, 0.93) | 0.83 (0.72, 0.95) | 0.86 (0.74, 0.98) | |||
| Lifting or carrying light loads, or climbing stairs often | 115 128 | 514 | 0.80 (0.69, 0.93) | 0.83 (0.71, 0.96) | 0.86 (0.74, 1.00) | |||
| Heavy lifting or carrying | 9 775 | 29 | 0.55 (0.38, 0.81) | 0.62 (0.42, 0.91) | 0.64 (0.43, 0.94) | |||
| Transportation Activity | ||||||||
| Years walked or biked to work | .051 | .081 | .084 | |||||
| < 1 | 555 972 | 2540 | 1.00 | 1.00 | 1.00 | |||
| 1–2 | 24 197 | 110 | 1.00 (0.83, 1.21) | 0.99 (0.82, 1.20) | 0.99 (0.82, 1.20) | |||
| 3–5 | 25 376 | 120 | 1.03 (0.86, 1.23) | 1.03 (0.86, 1.24) | 1.03 (0.86, 1.24) | |||
| 6–9 | 10 357 | 33 | 0.69 (0.49, 0.97) | 0.69 (0.49, 0.98) | 0.70 (0.50, 0.98) | |||
| ≥ 10 | 16 090 | 63 | 0.84 (0.65, 1.08) | 0.86 (0.67, 1.11) | 0.86 (0.67, 1.11) | |||
| Sedentary Behavior | ||||||||
| Television or video watching, h/day | .303 | .493 | .935 | |||||
| < 3 | 220 736 | 1013 | 1.00 | 1.00 | 1.00 | |||
| 3–4 | 272 210 | 1243 | 0.97 (0.89, 1.05) | 1.02 (0.94, 1.11) | 1.00 (0.92, 1.09) | |||
| 5–6 | 103 031 | 438 | 0.89 (0.80, 0.99) | 0.96 (0.86, 1.08) | 0.93 (0.83, 1.05) | |||
| 7–8 | 18 990 | 90 | 0.99 (0.80, 1.23) | 1.08 (0.87, 1.34) | 1.04 (0.84, 1.30) | |||
| ≥ 9 | 17 025 | 82 | 1.03 (0.82, 1.28) | 1.17 (0.93, 1.47) | 1.12 (0.89, 1.41) | |||
| Sitting, h/day | .006 | .101 | .243 | |||||
| < 3 | 136 447 | 564 | 1.00 | 1.00 | 1.00 | |||
| 3–4 | 186 096 | 856 | 1.11 (0.99, 1.23) | 1.08 (0.97, 1.20) | 1.07 (0.96, 1.19) | |||
| 5–6 | 171 157 | 803 | 1.14 (1.03, 1.27) | 1.10 (0.98, 1.22) | 1.08 (0.97, 1.20) | |||
| 7–8 | 89 698 | 419 | 1.17 (1.03, 1.33) | 1.11 (0.97, 1.26) | 1.08 (0.95, 1.23) | |||
| ≥ 9 | 48 594 | 224 | 1.19 (1.02, 1.39) | 1.12 (0.95, 1.31) | 1.08 (0.92, 1.27) | |||
Note. RR = relative risk; CI = confidence interval. Person-years are rounded to the nearest whole number. The total number of participants was 97 039.
Adjusted for age, energy intake (kilocalories per day), recreational moderate–vigorous physical activity (0, 1–3, or ≥ 4 h/wk), parity or age at first live birth (never, < 20, < 25, < 30, or ≥ 30 years), menopausal hormone therapy use (never, current, or former), number of breast biopsies (0, 1, 2, or 3), smoking (ever or never), alcohol intake in grams per day (0, < 5, < 15, < 30, or ≥ 30), race (White, Black, or other), education (< 12 y, high school graduate, some college, or college graduate).
Adjusted for same covariates as in multivariate 1 plus body mass index (continuous).