Table 1.
Descriptive characteristics of UK Biobank participants
| General characteristics | |
|---|---|
| Total (N) | 502 521 |
| Sex | |
| Female | 273 391 (54.4%) |
| Male | 229 130 (45.6%) |
| Age at recruitment (years), mean ± SD | 56.5 ± 8.1 |
| Health characteristics | |
| BMIa (n = 491 283) | |
| Underweight (<18.5 kg/m2) | 2623 (1.0%) |
| Healthy (18.5–24.9 kg/m2) | 157 409 (31.0%) |
| Overweight (25–29.9 kg/m2) | 209 092 (42.6%) |
| Obese (>30 kg/m2) | 122 159 (24.9%) |
| Smoking status (n = 499 571) | |
| Never smoker | 273 527 (54.8%) |
| Former smoker | 173 067 (34.6%) |
| Current smoker | 52 977 (10.6%) |
| Alcohol intake frequency (n = 501 019) | |
| Daily or almost daily | 101 774 (20.3%) |
| Three or four times a week | 115 441 (23.0%) |
| Once or twice a week | 129 292 (25.8%) |
| Occasional drinkersb | 113 865 (22.7%) |
| Never drinker | 40 647 (8.2%) |
| High blood pressure medication (n = 224 545) | |
| Yes | 56 085 (25.0%) |
| No | 168 460 (75.0%) |
| Socioeconomic status characteristics | |
| Economic statusc (n = 496 767) | |
| Economically active | 287 162 (57.7%) |
| Economically inactive | 209 605 (42.3%) |
| Townsend deprivation index at recruitment, quintiles (n = 501 898) | |
| 1 (least deprived) | 100 679 (20.3%) |
| 2 | 100 127 (20.2%) |
| 3 | 100 346 (19.2%) |
| 4 | 100 372 (20.3%) |
| 5 (most deprived) | 100 374 (20.0%) |
| Average total household income before tax (n = 425 350) | |
| <£18 000 | 97 200 (22.9%) |
| £18 000 to £30 999 | 108 178 (25.4%) |
| £31 000 to £51 999 | 110 773 (26.0%) |
| £52 000 to £100 000 | 86 267 (20.3%) |
| >£100 000 | 22 932 (5.4%) |
| Season of blood drawd | |
| Spring | 146 470 (29.2%) |
| Summer | 131 999 (26.3%) |
| Autumn | 119 389 (23.7%) |
| Winter | 104 663 (20.8%) |
| Length of time at residence (years), mean ± SD (n = 499 846) | 17.4 ± 12.1 |
| Exposure characteristics | |
| L den, dB[A], mean ± SD, range (n = 495 155) | 56.1 ± 4.3 (51.5–93.4) |
| Low (≤55 dB[A]) | 254 874 (51.4%) |
| Low–medium (>55 to ≤60 dB[A]) | 179 765 (36.3%) |
| Medium–high (>60 to ≤65 dB[A]) | 29 024 (5.9%) |
| High (>65 dB[A]) | 31 492 (6.4%) |
| L night, dB[A], mean ± SD, range (n = 495 155) | 46.6 ± 4.3 (42.1–93.9) |
| Low (≤45 dB[A]) | 205 930 (41.6%) |
| Low–medium (>45 to ≤50 dB[A]) | 222 522 (44.9%) |
| Medium–high (>50 to ≤55 dB[A]) | 33 073 (6.7%) |
| High (>55 dB[A]) | 33 630 (6.8%) |
| NO2 (μg/m3), mean ± SD, range (n = 495 155) | 26.7 ± 7.6 (12.9–108.5) |
| PM2.5 (μg/m3), mean ± SD, range (n = 461 228) | 9.99 ± 1.1 (8.2–21.3) |
| L den, NO2, r s | 0.23 |
| L den, PM2.5, r s | 0.24 |
| Outcome characteristics,e | |
| Systolic blood pressure (mmHg), mean ± SD, range (n = 456 977) | 137.8 ± 18.6, (65.0–253.5) |
| Diastolic blood pressure (mmHg), mean ± SD, range (n = 456 989) | 82.2 ±10.1 (36.5–120.0) |
| C-reactive protein (mg/L), median ± IQR, range (n = 449 139) | 1.3 ± 1.9 (0.1–10.0) |
| Triglycerides (mmol/L), median ± IQR, range (n = 469 226) | 1.8 ± 1.0 (0.2–11.3) |
| Glycated haemoglobin (mmol/mol), mean ± SD, range (n = 455 865) | 35.4 ± 4.3 (15.0–54.0) |
| Self-reported hypertension (n = 500 298) | |
| Yes | 135 539 (27.1%) |
| No | 364 539 (72.9%) |
BMI, body mass index; IQR, interquartile range; NO2, nitrogen dioxide; PM2.5, particulate matter with a diameter <2.5 μm; SD, standard deviation; WHO, World Health Organisation.
a
BMI categorized according to WHO and UK classifications.
b
Includes individuals who drink on special occasions only and individuals who drink ∼1–2 times a month.
c
Economic status refers to paid employment and unpaid employment.
d
Based on date attending assessment centre: winter (December, January, February), spring (March, April, May), summer (June, July August), autumn (September, October, November).
e
Median ± IQR used where mean differed from median by >10%.