Baseline characteristics of study participants according to categories of the diet quality score
| All participants (n=592 571) | Low hPDI (Q1; n=148 143) | Intermediate hPDI (Q2-Q3; n=296 286) | High hPDI (Q4; n=148 142) | |
| hPDI score, median (P25–P75) | 50 (47–54) | 45 (43–47) | 51 (49–52) | 56 (55–58) |
| Demographic characteristics | ||||
| Age, years | 56 (44–65) | 52 (41–62) | 57 (45–66) | 57 (45–65) |
| ≥18–24 | 14 397 (2.4) | 5146 (3.4) | 5846 (2.0) | 3405 (2.3) |
| 25–34 | 52 922 (8.9) | 16 535 (11.2) | 23 150 (7.8) | 13 237 (8.9) |
| 35–44 | 86 251 (14.6) | 26 907 (18.2) | 40 145 (13.5) | 19 199 (13.0) |
| 45–54 | 125 802 (21.2) | 34 890 (23.6) | 62 491 (21.1) | 28 421 (19.2) |
| 55–64 | 158 637 (26.8) | 34 279 (23.1) | 81 837 (27.6) | 42 521 (28.7) |
| ≥65 | 153 810 (26.0) | 30 215 (20.4) | 82 413 (27.8) | 41 182 (27.8) |
| Missing | 752 (0.1) | 171 (0.1) | 404 (0.1) | 177 (0.1) |
| Sex, no (%) | ||||
| Male | 187 450 (31.6) | 58 199 (39.3) | 93 162 (31.4) | 36 089 (24.4) |
| Female | 404 126 (68.2) | 89 706 (60.5) | 202 605 (68.4) | 111 815 (75.5) |
| Prefer not to say | 995 (0.2) | 238 (0.2) | 519 (0.2) | 238 (0.2) |
| Race*, no (%) | ||||
| White | 568 770 (96.0) | 141 365 (95.4) | 284 804 (96.1) | 142 601 (96.3) |
| Black | 4328 (0.7) | 1466 (1.0) | 2053 (0.7) | 809 (0.5) |
| Asian | 10 435 (1.8) | 2954 (1.9) | 5043 (1.7) | 2438 (1.6) |
| Other | 7228 (1.2) | 1925 (1.3) | 3463 (1.2) | 1840 (1.2) |
| Missing | 1810 (0.3) | 433 (0.3) | 923 (0.3) | 454 (0.3) |
| Country, no (%) | ||||
| UK | 543 984 (91.8) | 135 360 (91.4) | 272 494 (92.0) | 136 130 (91.9) |
| USA | 48 587 (8.2) | 12 783 (8.6) | 23 792 (8.0) | 12 012 (8.1) |
| Index of deprivation, no (%)† | ||||
| Most deprived, decile 1 | 13 416 (2.3) | 4696 (3.1) | 6163 (2.1) | 2557 (1.7) |
| Least deprived, decile 10 | 103 608 (17.5) | 23 122 (15.6) | 53 652 (18.1) | 26 834 (18.1) |
| Missing | 40 759 (6.9) | 10 489 (7.1) | 20 249 (6.8) | 10 021 (6.8) |
| Population density, km2, no (%)† | ||||
| <500 | 119 782 (20.2) | 28 139 (19.0) | 61 230 (20.7) | 30 413 (20.5) |
| 500–1999 | 90 541 (15.3) | 23 631 (16.0) | 45 902 (15.5) | 21 008 (14.2) |
| 2000–4999 | 94 345 (15.9) | 24 813 (16.7) | 47 233 (15.9) | 22 299 (15.1) |
| ≥5000 | 244 295 (41.2) | 60 156 (40.6) | 120 319 (40.6) | 63 820 (43.1) |
| Missing | 43 608 (7.4) | 11 404 (7.7) | 21 602 (7.3) | 10 602 (7.2) |
| Healthcare worker, yes, no (%) | 41 141 (6.9) | 10 633 (2.3) | 20 183 (6.8) | 10 325 (7.0) |
| Lifestyle characteristics | ||||
| Smoking status, no (%) | ||||
| Never | 475 347 (81.9) | 113 165 (79.0) | 238 192 (81.9) | 123 990 (84.6) |
| Former | 87 901 (15.1) | 22 683 (15.8) | 44 771 (15.4) | 20 447 (13.9) |
| Current | 17 401 (3.0) | 7402 (5.2) | 7837 (2.6) | 2162 (1.5) |
| Physical activity | ||||
| <1 day/week | 106 294 (17.9) | 37 258 (25.2) | 50 713 (17.1) | 18 323 (12.4) |
| 1–2 days/week | 224 606 (37.9) | 59 325 (40.0) | 113 749 (38.4) | 51 532 (34.8) |
| 3–4 days/week | 143 548 (24.2) | 30 009 (20.3) | 73 601 (24.8) | 39 938 (27.0) |
| ≥5 days/week | 117 007 (19.7) | 21 164 (14.3) | 57 701 (19.5) | 38 142 (25.7) |
| Missing | 1116 (0.2) | 387 (0.3) | 522 (0.2) | 207 (0.1) |
| Body mass index, kg/m2 | 25.1 (22.6–28.7) | 26.6 (23.6–30.7) | 25.2 (22.7–28.5) | 24.0 (21.8–26.9) |
| <18.5 | 12 004 (2.0) | 2680 (1.8) | 5540 (1.9) | 3784 (2.6) |
| 18.5–24.9 | 277 536 (46.8) | 52 109 (35.2) | 138 503 (46.7) | 86 924 (58.7) |
| 25–29.9 | 189 197 (31.9) | 51 517 (34.8) | 97 919 (33.0) | 39 761 (26.8) |
| ≥30 | 113 056 (19.1) | 41 655 (28.1) | 53 909 (18.2) | 17 492 (11.8) |
| Missing | 778 (0.1) | 182 (0.1) | 415 (0.1) | 181 (0.1) |
| Mask wearing, no (%)‡ | ||||
| Most of the time/always | 437 782 (73.9) | 113 202 (76.4) | 218 402 (73.7) | 106 178 (71.6) |
| Never/sometimes | 152 551 (25.7) | 34 240 (23.1) | 76 809 (25.9) | 41 502 (28.0) |
| Missing | 2238 (0.4) | 701 (0.5) | 1075 (0.4) | 462 (0.3) |
| Clinical history, yes, no (%) | ||||
| Diabetes | 20 058 (3.4) | 6079 (4.1) | 10 158 (3.4) | 3821 (2.6) |
| Heart disease | 20 376 (3.4) | 5200 (3.5) | 10 660 (3.6) | 4516 (3.0) |
| Cancer | 6559 (1.9) | 1643 (1.8) | 3348 (1.9) | 1568 (1.8) |
| Lung disease | 62 999 (10.6) | 17 534 (11.8) | 31 227 (10.5) | 14 238 (9.6) |
| Kidney disease | 5134 (0.9) | 1492 (1.0) | 2594 (0.9) | 1048 (0.7) |
Values are median (P25–P75) for continuous variables; numbers and (percentages) for categorical variables.
hPDI ranges from 0 to 70, with higher scores indicating higher adherence to a healthy plant-based diet.
*Race was self-reported by the participants.
†Index of deprivation and population density were generated using zipcode or postcode information linked with census track data. Country-specific deprivation indices were generated (online supplemental file).
‡Mask wearing information was collapsed into two categories: participants who wore masks ‘none of the time or sometimes’, and those who reported wearing masks ‘most of time/always’.
hPDI, healthful Plant-Based Diet Index.