Table 3.
Association between BMI and all cause mortality stratified by number of low risk lifestyle factors*
| No of low risk factors | BMI | P value for trend† | |||||||
|---|---|---|---|---|---|---|---|---|---|
| <18.5 | 18.5-22.4 | 22.5-24.9 | 25.0-27.4 | 27.5-29.9 | 30.0-34.9 | 35.0-39.9 | ≥40 | ||
| None | |||||||||
| No of deaths/PYs | 266/8953 | 2163/144 535 | 2257/153 398 | 2169/137 313 | 1133/73 527 | 1058/70 562 | 342/20 651 | 161/8488 | — |
| Crude IR (/105PY) | 2971 | 1497 | 1471 | 1580 | 1541 | 1499 | 1656 | 1897 | — |
| HR (95% CI)‡ | 2.37 (2.08 to 2.69) | 1.24 (1.17 to 1.32) | 1.0 | 1.00 (0.94 to 1.06) | 1.03 (0.96 to 1.10) | 1.11 (1.03 to 1.19) | 1.50 (1.34 to 1.68) | 1.80 (1.53 to 2.11) | 0.81 |
| One | |||||||||
| No of deaths/PYs | 237/13 525 | 2485/285 415 | 3091/320 339 | 3029/282 160 | 1604/142 850 | 1423/129 032 | 459/37 537 | 207/13 127 | — |
| Crude IR (/105PY) | 1752 | 871 | 965 | 1074 | 1123 | 1103 | 1223 | 1577 | — |
| HR (95% CI)‡ | 1.89 (1.65 to 2.16) | 1.11 (1.06 to 1.17) | 1.0 | 1.00 (0.95 to 1.05) | 1.11 (1.05 to 1.18) | 1.22 (1.15 to 1.30) | 1.59 (1.44 to 1.75) | 2.13 (1.84 to 2.45) | <0.001 |
| Two | |||||||||
| No of deaths/PYs | 92/9274 | 1307/228 238 | 1746/255 868 | 1535/201 763 | 682/91 465 | 556/69 328 | 164/16 304 | 71/5725 | — |
| Crude IR (/105PY) | 992 | 573 | 682 | 761 | 746 | 802 | 1006 | 1240 | — |
| HR (95% CI)‡ | 1.57 (1.27 to 1.94) | 1.05 (0.97 to 1.13) | 1.0 | 1.03 (0.96 to 1.10) | 1.13 (1.03 to 1.23) | 1.35 (1.22 to 1.48) | 2.09 (1.78 to 2.46) | 2.40 (1.89 to 3.05) | <0.001 |
| Three or four | |||||||||
| No of deaths/PYs | 20/3752 | 428/108 310 | 609/125 375 | 407/85 914 | 190/30 710 | 87/16 837 | 23/2835 | 13/1098 | — |
| Crude IR (/105PY) | 533 | 395 | 486 | 474 | 619 | 517 | 811 | 1184 | — |
| HR (95% CI)‡ | 1.21 (0.77 to 1.91) | 0.98 (0.86 to 1.11) | 1.0 | 0.96 (0.84 to 1.09) | 1.26 (1.07 to 1.48) | 1.40 (1.11 to 1.76) | 2.32 (1.52 to 3.54) | 3.50 (2.00 to 6.13) | <0.001 |
PY=person year; IR=incident rate.
*Low risk lifestyle factors include never smoking, exercise ≥30 min/day at moderate or vigorous intensity, score on alternate healthy eating index in upper two fifths, and moderate alcohol consumption (5-15 g alcohol/day in women, 5-30 g alcohol/day in men). Each factor coded as 0 or 1 and three scores summed, so healthy lifestyles scores were 0, 1, 2, 3, or 4 (healthiest). Non-linear relation between BMI and risk of all cause mortality significant only among people with no low risk lifestyle factor (P<0.001 for non-linear trend), tested with likelihood ratio method by comparing model with linear term only with model with both linear and cubic spline terms stratified by numbers of low risk lifestyle factors. P<0.001 for multiplicative interaction between BMI (8 categories) and numbers of low risk factors comparing 2 log likelihood of adjusted models with and without cross product interaction term.
†P for linear trend tested by treating BMI as continuous variable.
‡Adjusted for age; race; current multivitamin use, and current aspirin use; family history of diabetes mellitus, myocardial infarction, or cancer; and, for women, menopausal status and hormone use.