Table 1 Characteristics of the study sample at wave 1 according to trajectory group
From: Trajectories of body mass index in adulthood and risk of subtypes of postmenopausal breast cancer
Total study sample | T1 «Normal-stable»a | T2 «Normal-overweight»a | T3 «Normal-obesity»a | T4 «Overweight- obesity»a | T5 «Obesity-decrease»a |
|---|---|---|---|---|---|
N = 148,866 | Mean ± SD or n (%) | Mean ± SD or n (%) | Mean ± SD or n (%) | Mean ± SD or n (%) | Mean ± SD or n (%) |
Wave 1 characteristics | |||||
Number of participants | 65,507 (44.0) | 60,440 (40.6) | 18,117 (12.2) | 3609 (2.4) | 1193 (0.8) |
Age at enrollment (yrs) | 49.1 ± 0.03 | 49.2 ± 0.03 | 48.5 ± 0.06 | 48.2 ± 0.14 | 53.9 ± 0.26 |
Age at menarche (yrs) | 13.5 ± 0.01 | 13.2 ± 0.01 | 12.9 ± 0.01 | 12.6 ± 0.02 | 13.1 ± 0.04 |
Parity | 2.1 ± 0.00 | 2.3 ± 0.01 | 2.3 ± 0.01 | 2.2 ± 0.02 | 2.3 ± 0.04 |
Age at first birth (yrs) | 24.4 ± 0.02 | 23.8 ± 0.02 | 23.6 ± 0.04 | 23.5 ± 0.08 | 23.9 ± 0.14 |
Breast cancer in mother | 3572 (5.5) | 3178 (5.3) | 926 (5.1) | 182 (5.4) | 67 (5.6) |
OC use | |||||
Current | 1261 (2.0) | 1142 (1.9) | 318 (1.8) | 81 (2.3) | 4 (0.3) |
Former | 36,961 (57.7) | 32,369 (54.9) | 9445 (53.4) | 1705 (48.7) | 459 (39.7) |
Never | 25,894 (40.4) | 25,508 (43.2) | 7922 (44.8) | 1713 (49.0) | 692 (59.9) |
MHT use | |||||
Current | 8949 (13.9) | 7349 (12.4) | 1722 (9.7) | 258 (7.3) | 206 (17.5) |
Former | 7415 (11.5) | 7166 (12.1) | 2112 (11.9) | 390 (11.0) | 141 (12.0) |
Never | 47,946 (74.6) | 44,965 (75.6) | 13,964 (78.5) | 2896 (81.7) | 832 (70.6) |
Smoking status | |||||
Current | 20,984 (32.2) | 17,985 (29.9) | 5101 (28.3) | 993 (27.6) | 518 (43.6) |
Former | 21,243 (32.6) | 21,780 (36.2) | 6585 (36.5) | 1316 (36.6) | 322 (27.1) |
Never | 23,033 (35.3) | 20,441 (34.0) | 6368 (35.3) | 1286 (35.8) | 349 (29.4) |
Physical activity | |||||
High | 13,826 (21.3) | 10,031 (16.7) | 2381 (13.3) | 358 (10.0) | 243 (20.8) |
Moderate | 38,527 (59.3) | 34,790 (58.0) | 9269 (51.6) | 1591 (44.6) | 633 (54.1) |
Low | 12,617 (19.4) | 15,141 (25.3) | 6315 (35.2) | 1621 (45.4) | 295 (25.2) |
Education (yrs) | |||||
≤ 9 | 11,591 (18.5) | 13,333 (23.1) | 4598 (26.5) | 978 (28.3) | 423 (39.1) |
10–12 | 20,531 (32.8) | 20,422 (35.4) | 6288 (36.3) | 1267 (36.7) | 381 (35.3) |
13–16 | 18,950 (30.3) | 15,970 (27.7) | 4481 (25.9) | 831 (24.1) | 199 (18.4) |
≥ 17 | 11,472 (18.3) | 7948 (13.8) | 1959 (11.3) | 379 (11.0) | 78 (7.2) |
BMI variables | |||||
BMI at age 18 (kg/m2) | 19.7 ± 0.01 | 21.1 ± 0.01 | 22.3 ± 0.02 | 24.9 ± 0.06 | 34.1 ± 0.10 |
BMI at wave 1 (kg/m2) | 21.4 ± 0.01 | 25.0 ± 0.01 | 29.6 ± 0.02 | 36.0 ± 0.07 | 25.4 ± 0.11 |
BMI at wave 2 (kg/m2) | 21.8 ± 0.01 | 25.7 ± 0.01 | 30.4 ± 0.02 | 36.5 ± 0.08 | 25.6 ± 0.13 |
BMI at wave 3 (kg/m2) | 22.1 ± 0.01 | 26.1 ± 0.02 | 30.9 ± 0.03 | 37.1 ± 0.11 | 26.2 ± 0.23 |
Predicted BMI variablesb | |||||
Age at overweight onset (yrs) | N/A | 46.5 ± 0.03 | 32.5 ± 0.04 | 21.9 ± 0.07 | 18.0 ± 0.01 |
Age at obesity onset (yrs) | N/A | N/A | 50.5 ± 0.06 | 35.9 ± 0.10 | 19.5 ± 0.24 |
Overweight duration (yrs) | N/A | 7.8 ± 0.03 | 23.1 ± 0.06 | 32.9 ± 0.13 | 35.4 ± 0.35 |
Obesity duration (yrs) | N/A | N/A | 4.6 ± 0.04 | 18.9 ± 0.14 | 8.4 ± 0.37 |
Overweight intensity (OWY) | N/A | 10.1 ± 0.01 | 72.5 ± 0.34 | 206.9 ± 1.61 | 123.6 ± 2.65 |
Obesity intensity (OBY) | N/A | N/A | 6.7 ± 0.10 | 76.4 ± 1.04 | 14.2 ± 0.92 |