Table 1.
Characteristics of study population at the time of BMI measure by WHO BMI category,19 restricted to individuals with follow-up available from 5 years after the BMI record
| Underweight (<18·5 kg/m2); n=112 077 | Healthy weight (18·5–24·9 kg/m2); n=1 793 989 | Overweight (25·0–29·9 kg/m2); n=1 151 359 | Obese (≥30·0 kg/m2); n=575 249* | Overall; n=3 632 674 | ||
|---|---|---|---|---|---|---|
| Time from BMI record date to end of follow-up (years) | ||||||
| Mean (SD) | 12·2 (5·4) | 13·1 (5·6) | 12·6 (5·4) | 11·5 (5·1) | 12·7 (5·5) | |
| Median (IQR) | 11 (7·8–15·6) | 12 (8·4–17·2) | 11·6 (8·1–16·1) | 10·4 (7·4–14·4) | 11·6 (8·1–16·3) | |
| Total follow-up included (millions of person-years) | 0·756 | 13·614 | 8·248 | 3·557 | 26·176 | |
| Age (years) | ||||||
| <30 | 73 653 (65·7%) | 769 152 (42·9%) | 271 837 (23·6%) | 124 965 (21·7%) | 1 239 607 (34·1%) | |
| 30–39 | 15 780 (14·1%) | 394 672 (22·0%) | 253 964 (22·1%) | 123 093 (21·4%) | 787 509 (21·7%) | |
| 40–49 | 7529 (6·7%) | 243 730 (13·6%) | 211 796 (18·4%) | 116 511 (20·3%) | 579 566 (16·0%) | |
| 50–59 | 4531 (4·0%) | 163 210 (9·1%) | 178 411 (15·5%) | 99 176 (17·2%) | 445 328 (12·3%) | |
| 60–69 | 4221 (3·8%) | 117 085 (6·5%) | 137 148 (11·9%) | 70 164 (12·2%) | 328 618 (9·0%) | |
| 70–79 | 3937 (3·5%) | 76 051 (4·2%) | 76 680 (6·7%) | 33 964 (5·9%) | 190 632 (5·2%) | |
| ≥80 | 2426 (2·2%) | 30 089 (1·7%) | 21 523 (1·9%) | 7376 (1·3%) | 61 414 (1·7%) | |
| Median (IQR) | 24·7 (19·2–35·5) | 32·7 (24·3–47·0) | 42·2 (30·6–56·8) | 43·3 (31·6–56·5) | 36·9 (26·6–52·4) | |
| Sex | ||||||
| Women | 78 745 (70·3%) | 1 068 110 (59·5%) | 518 896 (45·1%) | 322 647 (56·1%) | 1 988 398 (54·7%) | |
| Men | 33 332 (29·7%) | 725 879 (40·5%) | 632 463 (54·9%) | 252 602 (43·9%) | 1 644 276 (45·3%) | |
| Smoking status | ||||||
| Never-smoker | 59 327 (52·9%) | 989 704 (55·2%) | 617 698 (53·6%) | 302 919 (52·7%) | 1 969 648 (54·2%) | |
| Current smoker | 41 272 (36·8%) | 559 478 (31·2%) | 312 427 (27·1%) | 147 707 (25·7%) | 1 060 884 (29·2%) | |
| Ex-smoker | 9828 (8·8%) | 231 269 (12·9%) | 214 542 (18·6%) | 121 130 (21·1%) | 576 769 (15·9%) | |
| Data missing | 1650 (1·5%) | 13 538 (0·8%) | 6692 (0·6%) | 3493 (0·6%) | 25 373 (0·7%) | |
| Alcohol use | ||||||
| Non-drinker | 27 058 (24·1%) | 277 594 (15·5%) | 169 072 (14·7%) | 105 930 (18·4%) | 579 654 (16·0%) | |
| Current drinker, 1–2 units per day | 56 496 (50·4%) | 1 083 931 (60·4%) | 674 329 (58·6%) | 317 722 (55·2%) | 2 132 478 (58·7%) | |
| Current drinker, 3–6 units per day | 5337 (4·8%) | 170 458 (9·5%) | 148 318 (12·9%) | 56 156 (9·8%) | 380 269 (10·5%) | |
| Current drinker, ≥7 units per day | 1835 (1·6%) | 28 469 (1·6%) | 21 958 (1·9%) | 11 634 (2·0%) | 63 896 (1·8%) | |
| Current drinker, unknown level | 5250 (4·7%) | 76 572 (4·3%) | 47 688 (4·1%) | 25 650 (4·5%) | 155 160 (4·3%) | |
| Ex-drinker | 2396 (2·1%) | 31 974 (1·8%) | 24 398 (2·1%) | 17 601 (3·1%) | 76 369 (2·1%) | |
| Data missing | 13 705 (12·2%) | 124 991 (7·0%) | 65 596 (5·7%) | 40 556 (7·1%) | 244 848 (6·7%) | |
| Any previous diabetes diagnosis | 885 (0·8%) | 25 896 (1·4%) | 38 903 (3·4%) | 39 323 (6·8%) | 105 007 (2·9%) | |
| Index of multiple deprivation | ||||||
| Quintile 1 (low) | 21 735 (19·4%) | 428 458 (23·9%) | 260 902 (22·7%) | 102 681 (17·8%) | 813 776 (22·4%) | |
| Quintile 2 | 21 840 (19·5%) | 392 644 (21·9%) | 255 758 (22·2%) | 115 817 (20·1%) | 786 059 (21·6%) | |
| Quintile 3 | 23 046 (20·6%) | 374 109 (20·9%) | 242 194 (21·0%) | 121 034 (21·0%) | 760 383 (20·9%) | |
| Quintile 4 | 22 960 (20·5%) | 329 436 (18·4%) | 214 904 (18·7%) | 120 965 (21·0%) | 688 265 (18·9%) | |
| Quintile 5 (high) | 22 324 (19·9%) | 267 155 (14·9%) | 176 289 (15·3%) | 114 098 (19·8%) | 579 866 (16·0%) | |
| Ethnicity | ||||||
| White | 36 317 (32·4%) | 619 968 (34·6%) | 428 065 (37·2%) | 235 071 (40·9%) | 1 319 421 (36·3%) | |
| South Asian | 5432 (4·8%) | 48 835 (2·7%) | 28 318 (2·5%) | 10 835 (1·9%) | 93 420 (2·6%) | |
| Black | 1474 (1·3%) | 23 675 (1·3%) | 20 772 (1·8%) | 14 292 (2·5%) | 60 213 (1·7%) | |
| Other | 2244 (2·0%) | 21 529 (1·2%) | 10 279 (0·9%) | 4170 (0·7%) | 38 222 (1·1%) | |
| Mixed | 648 (0·6%) | 8357 (0·5%) | 4499 (0·4%) | 2374 (0·4%) | 15 878 (0·4%) | |
| Data missing | 65 962 (58·9%) | 1 071 625 (59·7%) | 659 426 (57·3%) | 308 507 (53·6%) | 2 105 520 (58·0%) | |
| Calendar year of first available BMI record | ||||||
| <1989 | 803 (0·7%) | 18 480 (1·0%) | 11 300 (1·0%) | 4414 (0·8%) | 34 997 (1·0%) | |
| 1990–94 | 16 549 (14·8%) | 379 351 (21·1%) | 233 344 (20·3%) | 83 708 (14·6%) | 712 952 (19·6%) | |
| 1995–99 | 22 241 (19·8%) | 400 716 (22·3%) | 252 260 (21·9%) | 111 507 (19·4%) | 786 724 (21·7%) | |
| 2000–04 | 28 235 (25·2%) | 416 163 (23·2%) | 279 589 (24·3%) | 153 742 (26·7%) | 877 729 (24·2%) | |
| 2005–09 | 36 201 (32·3%) | 479 627 (26·7%) | 311 622 (27·1%) | 181 477 (31·5%) | 1 008 927 (27·8%) | |
| ≥2010 | 8048 (7·2%) | 99 652 (5·6%) | 63 244 (5·5%) | 40 401 (7·0%) | 211 345 (5·8%) | |
Data are n (%), mean (SD), or median (IQR).
Among 575 249 obese individuals, 405 005 (70·4%), had obesity class 1 (BMI 30–34·9 kg/m2), 121 891 (21·2%) had obesity class 2 (BMI 35–39·9 kg/m2), and 48 353 (8·4%) had obesity class 3 (BMI ≥40 kg/m2). A further breakdown of these characteristics by sex as well as BMI category is given in the appendix. Characteristics are at the time of the first BMI record used in study where applicable; smoking was assigned by use of the record from same date as the BMI record or within 1 year before where available (for 3 000 050 [83%] patients), or by use of the nearest record in year after the BMI record (160 790 [4%]), or by use of the nearest record >1 year before the BMI record (285 817 [8%]), or by use of the nearest record >1 year after the BMI record (160 427 [4%]); a similar algorithm was used for alcohol; for ethnicity, the earliest available record was used.