Table 6.
The joint effects of sitting while watching television and different sedentary behaviours on all–cause mortality in the Multiethnic Cohort Study, 1993–2007
| Men |
Women |
|||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Daily sitting watching television (hours) |
Daily sitting watching television (hours) |
|||||||||||||
|
<1 |
1–4 |
≥5 |
<1 |
1–4 |
≥5 |
|||||||||
| Additional sedentary behaviour | No. deaths | HR (95% CI)a | No. deaths | HR (95% CI)a | No. deaths | HR (95% CI)a | Pintb | No. deaths | HR (95% CI)a | No. deaths | HR (95% CI)a | No. deaths | HR (95% CI)a | Pintb |
| Sitting in other leisure activities, h/day | ||||||||||||||
| <1 | 683 | 1.00 | 3366 | 0.98 (0.90–1.06) | 573 | 1.14 (1.02–1.28) | 0.70 | 489 | 1.00 | 1800 | 0.92 (0.83–1.02) | 356 | 1.34 (1.17–1.54) | <0.01 |
| 1–2 | 315 | 0.88 (0.76–1.00) | 3326 | 0.98 (0.90–1.07) | 573 | 1.14 (1.02–1.28) | 297 | 0.82 (0.71–0.95) | 2828 | 0.95 (0.86–1.05) | 529 | 1.26 (1.11–1.43) | ||
| ≥3 | 136 | 1.05 (0.87–1.27) | 1312 | 1.04 (0.94–1.14) | 338 | 1.24 (1.08–1.42) | 157 | 1.09 (0.91–1.32) | 1640 | 1.04 (0.94–1.16) | 426 | 1.25 (1.09–1.43) | ||
| Sitting in a car or bus, h/day | ||||||||||||||
| <1 | 700 | 1.00 | 4655 | 1.01 (0.93–1.10) | 894 | 1.17 (1.05–1.29) | 0.28 | 643 | 1.00 | 4045 | 1.01 (0.93–1.10) | 854 | 1.33 (1.19–1.48) | 0.23 |
| 1–2 | 323 | 0.96 (0.84–1.09) | 2612 | 1.01 (0.93–1.10) | 461 | 1.18 (1.04–1.33) | 241 | 1.03 (0.88–1.20) | 1795 | 1.01 (0.92–1.10) | 367 | 1.34 (1.17–1.54) | ||
| ≥3 | 111 | 1.05 (0.85–1.29) | 737 | 0.99 (0.89–1.11) | 129 | 1.29 (1.07–1.57) | 59 | 0.98 (0.75–1.29) | 428 | 1.06 (0.94–1.21) | 90 | 1.34 (1.06–1.69) | ||
| Sitting at meals, h/day | ||||||||||||||
| <1 | 855 | 1.00 | 5028 | 1.00 (0.93–1.07) | 877 | 1.17 (1.06–1.29) | 0.0495 | 686 | 1.00 | 3910 | 1.03 (0.95–1.12) | 746 | 1.35 (1.21–1.50) | 0.49 |
| 1–2 | 259 | 0.92 (0.79–1.06) | 2758 | 0.99 (0.92–1.07) | 550 | 1.16 (1.04–1.30) | 236 | 1.11 (0.95–1.29) | 2127 | 1.05 (0.96–1.15) | 505 | 1.44 (1.28–1.62) | ||
| ≥3 | 19 | 1.09 (0.68–1.74) | 218 | 1.25 (1.07–1.45) | 58 | 1.39 (1.05–1.83) | 21 | 1.50 (0.95–2.37) | 231 | 1.30 (1.11–1.52) | 60 | 1.41 (1.06–1.86) | ||
| Sitting at work, h/dayc | ||||||||||||||
| <1 | 244 | 1.00 | 1480 | 0.93 (0.80–1.07) | 242 | 1.14 (0.95–1.38) | 0.32 | 185 | 1.00 | 902 | 0.86 (0.72–1.02) | 142 | 1.01 (0.81–1.27) | 0.33 |
| 1–4 | 314 | 0.91 (0.76–1.10) | 2330 | 0.90 (0.79–1.04) | 319 | 1.08 (0.90–1.30) | 233 | 0.88 (0.70–1.10) | 1674 | 0.88 (0.74–1.05) | 292 | 1.25 (1.01–1.55) | ||
| ≥5 | 199 | 0.80 (0.66–0.97) | 1194 | 0.89 (0.77–1.03) | 100 | 1.16 (0.91–1.48) | 170 | 0.77 (0.62–0.96) | 1072 | 0.85 (0.71–1.03) | 105 | 1.32 (1.00–1.74) | ||
HR, hazard ratio; CI, confidence interval; Pint, P–value for interaction.
aHazard ratios were calculated with age as the time metric, adjusted for following variables but the relevant variable: 5–year age groups at cohort entry, education, ethnicity, history of hypertension or diabetes at enrolment, alcohol consumption, energy intake, physical activity (METs per week for moderate activity, vigorous work and strenuous sports), trends of hours for total sitting time, proportion contributed by other sitting behaviours, and smoking history by inclusion of the following variables: [smoking status, average number of cigarettes, average number of cigarettes squared, number of years smoked (time dependent), number of years since quitting (time dependent), and interactions between ethnicity and the smoking variables].
bInteraction was assessed by a Wald test of the cross–product term of the two sitting activities being considered in models including total sitting time and the proportion of sitting time contributed by each type of sitting.
cRestricted to subjects reporting any time sitting at work.