Table 1.
Baseline characteristics of participants from US National Health and Nutrition Examination Survey (US NHANES) and UK Biobank according to socioeconomic status (SES).* Values are numbers (percentages) unless stated otherwise
| Characteristics | US NHANES | UK Biobank | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Total population (n=44 462) | High SES† (n=10 469) | Medium SES† (n=20 729) | Low SES† (n=13 264) | Total population (n=399 537) | High SES‡ (n=79 697) | Medium SES‡ (n=210 935) | Low SES‡ (n=108 905) | ||
| Mean age (95% CI) (years) | 46.5 (46.1 to 46.9) | 45.9 (45.3 to 46.4) | 47.7 (47.2 to 48.2) | 44.8 (44.2 to 45.3) | 56.1 (56.1 to 56.1) | 52.5 (52.4 to 52.5) | 55.7 (55.7 to 55.8) | 59.5 (59.5 to 59.5) | |
| Men | 21 869 (48.7) | 5335 (50.9) | 10 357 (48.4) | 6177 (45.8) | 189 813 (47.5) | 40 990 (51.4) | 101 484 (48.1) | 47 339 (43.5) | |
| White ethnicity or race | 21 392 (73.6) | 6630 (84.0) | 10 878 (76.0) | 3884 (50.8) | 382 053 (95.6) | 76 596 (96.1) | 202 429 (96.0) | 103 028 (94.6) | |
| Married | 24 223 (57.4) | 6987 (68.7) | 11 860 (58.1) | 5376 (37.0) | - | - | - | - | |
| Household income§: | |||||||||
| High | 10 840 (34.6) | 8162 (81.0) | 2653 (15.9) | 25 (0.3) | 105 098 (26.3) | 78 565 (98.6) | 25 914 (12.3) | 619 (0.6) | |
| Medium | 24 629 (52.0) | 2176 (18.0) | 17 208 (80.3) | 5245 (43.1) | 206 809 (51.8) | 1132 (1.4) | 185 021 (87.7) | 20 656 (19.0) | |
| Low | 8993 (13.4) | 131 (1.0) | 868 (3.7) | 7994 (56.6) | 87 630 (21.9) | 0 | 0 | 87 630 (80.5) | |
| Occupation: | |||||||||
| Employed, student, or retired | 35 382 (81.7) | 9787 (92.8) | 18 637 (89.1) | 6958 (46.2) | 372 167 (93.1) | 75 242 (94.4) | 207 951 (98.6) | 88 974 (81.7) | |
| Upper socioeconomic index | 7267 (22.7) | 6325 (61.2) | 697 (3.8) | 245 (2.1) | - | - | - | - | |
| Lower socioeconomic index | 28 115 (59.0) | 3462 (31.6) | 17 940 (85.3) | 6713 (44.1) | - | - | - | - | |
| Unemployed | 9080 (18.3) | 682 (7.2) | 2092 (11.0) | 6306 (53.8) | 27 370 (6.9) | 4455 (5.6) | 2984 (1.4) | 19 931 (18.3) | |
| Education: | |||||||||
| College or above | 19 747 (55.1) | 10 152 (96.6) | 7394 (39.1) | 2201 (22.4) | 188 002 (47.1) | 63 753 (80.0) | 97 653 (46.3) | 26 596 (24.4) | |
| High school or equivalent | 11 511 (26.4) | 317 (3.4) | 8750 (44.7) | 2444 (22.8) | 153 752 (38.5) | 15 944 (20.0) | 103 822 (49.2) | 33 986 (31.2) | |
| Less than high school | 13 204 (18.5) | 0 | 4585 (16.2) | 8619 (54.8) | 57 783 (14.5) | 0 | 9460 (4.5) | 48 323 (44.4) | |
| Health insurance: | |||||||||
| Private | 26 795 (68.8) | 9278 (90.4) | 16 448 (79.6) | 1069 (7.5) | - | - | - | - | |
| Public only | 8907 (14.5) | 745 (5.7) | 1896 (7.8) | 6266 (44.9) | - | - | - | - | |
| None | 8760 (16.6) | 446 (4.0) | 2385 (12.5) | 5929 (47.6) | - | - | - | - | |
| More accultured | 37 584 (91.5) | 9818 (96.1) | 18 466 (93.2) | 9300 (79.6) | 367 865 (92.1) | 71 696 (90.0) | 196 119 (93.0) | 100 050 (91.9) | |
| Never smoking | 22 835 (50.5) | 6330 (59.7) | 10 369 (47.8) | 6136 (41.6) | 218 975 (54.8) | 49 681 (62.3) | 117 780 (55.8) | 51 514 (47.3) | |
| No heavy alcohol consumption | 41 747 (92.3) | 9817 (92.5) | 19 535 (92.6) | 12 395 (91.3) | 251 900 (63.0) | 45 264 (56.8) | 131 045 (62.1) | 75 591 (69.4) | |
| Top third of LTPA | 12 956 (34.0) | 4507 (45.6) | 5824 (30.4) | 2625 (22.6) | 133 182 (33.3) | 32 993 (41.4) | 71 688 (34.0) | 28 501 (26.2) | |
| Healthy diet¶ | 19 321 (43.6) | 5534 (52.5) | 8803 (41.0) | 4984 (34.9) | 56 892 (14.2) | 10 826 (13.6) | 29 278 (13.9) | 16 788 (15.4) | |
| BMI: | |||||||||
| 18.5-24.9 | 13 827 (33.4) | 3568 (36.2) | 6443 (32.6) | 3816 (30.6) | 131 018 (32.8) | 31 920 (40.1) | 68 872 (32.7) | 30 226 (27.8) | |
| <18.5 | 755 (1.8) | 149 (1.4) | 309 (1.7) | 297 (2.7) | 1998 (0.5) | 388 (0.5) | 926 (0.4) | 684 (0.6) | |
| 25.0-29.9 | 15 294 (33.4) | 3684 (34.8) | 7163 (33.3) | 4447 (31.3) | 170 781 (42.7) | 33 504 (42.0) | 91 756 (43.5) | 45 521 (41.8) | |
| ≥30.0 | 14 586 (31.4) | 3068 (27.6) | 6814 (32.5) | 4704 (35.4) | 95 740 (24.0) | 13 885 (17.4) | 49 381 (23.4) | 32 474 (29.8) | |
| Self-reported comorbidities: | |||||||||
| Hypertension | 14 746 (29.4) | 2864 (24.9) | 7171 (31.2) | 4711 (32.8) | 112 082 (28.1) | 15 123 (19.0) | 56 087 (26.6) | 40 872 (37.5) | |
| Diabetes | 4680 (7.6) | 653 (4.7) | 2116 (8.2) | 1911 (11.2) | 19 819 (5.0) | 2178 (2.7) | 8966 (4.3) | 8675 (8.0) | |
| CVD | 4609 (8.1) | 597 (4.3) | 2232 (8.9) | 1780 (12.7) | 75 020 (18.8) | 8974 (11.3) | 35 280 (16.7) | 30 766 (28.3) | |
| Cancer | 4048 (9.2) | 1034 (9.7) | 2160 (9.7) | 854 (7.3) | 33 816 (8.5) | 5252 (6.6) | 17 121 (8.1) | 11 443 (10.5) | |
| Emphysema, chronic bronchitis, or COPD | 3238 (7.6) | 474 (4.6) | 1502 (7.7) | 1262 (12.2) | 8847 (2.2) | 813 (1.0) | 3631 (1.7) | 4403 (4.0) | |
BMI=body mass index; COPD=chronic obstructive pulmonary disease; CVD=cardiovascular disease; LTPA=leisure time physical activity.
In US NHANES, all estimates accounted for complex survey designs, and P values were calculated using analysis of variance adjusting for sampling weights and Rao-Scott χ2 test for continuous and categorical variables, respectively. In UK Biobank, P values were calculated using analysis of variance and χ2 test for continuous and categorical variables, respectively. All P values were <0.001, except for heavy alcohol consumption (P=0.058).
SES in US NHANES was generated through latent class analysis using information on family income to poverty ratio, occupation, education level, and health insurance.
SES in UK Biobank was generated through latent class analysis using the information on household income, employment status, and education level.
In US NHANES, ≥4, >1 to <4, and ≤1 of family income to poverty ratios represented the high, medium, and low family income level, respectively. In UK Biobank, <£18 000 ($25 000; €21 000), £18 000-£51 999, and ≥£52 000 of average total household income before tax represented the high, medium, and low family income level, respectively.
In US NHANES III, healthy diet denoted the top two fifths of healthy eating index-1995 score. In the continuous US NHANES, healthy diet denoted the top two fifths of healthy eating index-2015 score. In UK Biobank, healthy diet denoted ideal intakes of ≥5 dietary components for cardiovascular health.