Table 1

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, years56 (44–65)52 (41–62)57 (45–66)57 (45–65)
 ≥18–2414 397 (2.4)5146 (3.4)5846 (2.0)3405 (2.3)
 25–3452 922 (8.9)16 535 (11.2)23 150 (7.8)13 237 (8.9)
 35–4486 251 (14.6)26 907 (18.2)40 145 (13.5)19 199 (13.0)
 45–54125 802 (21.2)34 890 (23.6)62 491 (21.1)28 421 (19.2)
 55–64158 637 (26.8)34 279 (23.1)81 837 (27.6)42 521 (28.7)
 ≥65153 810 (26.0)30 215 (20.4)82 413 (27.8)41 182 (27.8)
 Missing752 (0.1)171 (0.1)404 (0.1)177 (0.1)
Sex, no (%)
 Male187 450 (31.6)58 199 (39.3)93 162 (31.4)36 089 (24.4)
 Female404 126 (68.2)89 706 (60.5)202 605 (68.4)111 815 (75.5)
 Prefer not to say995 (0.2)238 (0.2)519 (0.2)238 (0.2)
Race*, no (%)
 White568 770 (96.0)141 365 (95.4)284 804 (96.1)142 601 (96.3)
 Black4328 (0.7)1466 (1.0)2053 (0.7)809 (0.5)
 Asian10 435 (1.8)2954 (1.9)5043 (1.7)2438 (1.6)
 Other7228 (1.2)1925 (1.3)3463 (1.2)1840 (1.2)
 Missing1810 (0.3)433 (0.3)923 (0.3)454 (0.3)
Country, no (%)
 UK543 984 (91.8)135 360 (91.4)272 494 (92.0)136 130 (91.9)
 USA48 587 (8.2)12 783 (8.6)23 792 (8.0)12 012 (8.1)
Index of deprivation, no (%)†
 Most deprived, decile 113 416 (2.3)4696 (3.1)6163 (2.1)2557 (1.7)
 Least deprived, decile 10103 608 (17.5)23 122 (15.6)53 652 (18.1)26 834 (18.1)
 Missing40 759 (6.9)10 489 (7.1)20 249 (6.8)10 021 (6.8)
Population density, km2, no (%)†
 <500119 782 (20.2)28 139 (19.0)61 230 (20.7)30 413 (20.5)
 500–199990 541 (15.3)23 631 (16.0)45 902 (15.5)21 008 (14.2)
 2000–499994 345 (15.9)24 813 (16.7)47 233 (15.9)22 299 (15.1)
 ≥5000244 295 (41.2)60 156 (40.6)120 319 (40.6)63 820 (43.1)
 Missing43 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 (%)
 Never475 347 (81.9)113 165 (79.0)238 192 (81.9)123 990 (84.6)
 Former87 901 (15.1)22 683 (15.8)44 771 (15.4)20 447 (13.9)
 Current17 401 (3.0)7402 (5.2)7837 (2.6)2162 (1.5)
Physical activity
 <1 day/week106 294 (17.9)37 258 (25.2)50 713 (17.1)18 323 (12.4)
 1–2 days/week224 606 (37.9)59 325 (40.0)113 749 (38.4)51 532 (34.8)
 3–4 days/week143 548 (24.2)30 009 (20.3)73 601 (24.8)39 938 (27.0)
 ≥5 days/week117 007 (19.7)21 164 (14.3)57 701 (19.5)38 142 (25.7)
 Missing1116 (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)
 <18.512 004 (2.0)2680 (1.8)5540 (1.9)3784 (2.6)
 18.5–24.9277 536 (46.8)52 109 (35.2)138 503 (46.7)86 924 (58.7)
 25–29.9189 197 (31.9)51 517 (34.8)97 919 (33.0)39 761 (26.8)
 ≥30113 056 (19.1)41 655 (28.1)53 909 (18.2)17 492 (11.8)
 Missing778 (0.1)182 (0.1)415 (0.1)181 (0.1)
Mask wearing, no (%)‡
 Most of the time/always437 782 (73.9)113 202 (76.4)218 402 (73.7)106 178 (71.6)
 Never/sometimes152 551 (25.7)34 240 (23.1)76 809 (25.9)41 502 (28.0)
 Missing2238 (0.4)701 (0.5)1075 (0.4)462 (0.3)
Clinical history, yes, no (%)
 Diabetes20 058 (3.4)6079 (4.1)10 158 (3.4)3821 (2.6)
 Heart disease20 376 (3.4)5200 (3.5)10 660 (3.6)4516 (3.0)
 Cancer6559 (1.9)1643 (1.8)3348 (1.9)1568 (1.8)
 Lung disease62 999 (10.6)17 534 (11.8)31 227 (10.5)14 238 (9.6)
 Kidney disease5134 (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.