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Table 1 Cohort characteristics by overall discretionary screen-time categories

From: Associations of discretionary screen time with mortality, cardiovascular disease and cancer are attenuated by strength, fitness and physical activity: findings from the UK Biobank study

  Screen-time categories (h.day− 1)
<2 2–3 4–5 >5
Socio-demographics
 Total n 65,374 204,470 95,877 25,368
 Women, n (%) 38,977 (59.6) 110,399 (54.0) 51,460 (53.7) 12,519 (49.4)
 Age (years), mean (SD) 54.0 (8.0) 55.5 (8.1) 57.8 (7.8) 56.8 (8.2)
 Deprivation index quintiles, n (%)
  Lower 22,447 (34.3) 74,332 (36.4) 31,308 (32.7) 6643 (26.2)
  Middle 21,683 (33.2) 70,242 (34.4) 32,612 (34.0) 7515 (29.6)
  Higher 21,244 (32.5) 59,896 (29.3) 31,957 (33.3) 11,210 (44.2)
 Professional qualifications, n (%)
  College or university degree 33,304 (55.8) 72,395 (40.7) 20,217 (28.2) 5872 (33.2)
  A levels/AS levels or equivalent 7943 (13.3) 25,182 (14.2) 9120 (12.7) 2136 (12.1)
  O levels/GCSEs or equivalent 10,408 (17.4) 45,118 (25.4) 23,125 (32.3) 5115 (28.9)
  CSEs or equivalent 2230 (3.7) 11,517 (6.5) 6666 (9.3) 1641 (9.3)
  NVQ or HND or HNC or equivalent 2840 (4.8) 13,182 (7.4) 7388 (10.3) 1881 (10.6)
  Other professional qualifications 2984 (5.0) 10,603 (6.0) 5178 (7.2) 1042 (5.9)
 Income categories, n (%)
  Less than £18,000 7366 (12.8) 28,761 (16.1) 22,871 (28.5) 7808 (36.8)
  £18,000 to £29,999 11,344 (19.7) 44,273 (24.8) 23,569 (29.4) 5047 (23.8)
  £30,000 to £51,999 15,613 (27.1) 52,221 (29.3) 19,823 (24.7) 4066 (19.2)
  £52,000 to £100,000 16,782 (29.2) 42,731 (24.0) 11,718 (14.6) 3277 (15.4)
  Greater than £100,000 6432 (11.2) 10,364 (5.8) 2180 (2.7) 1025 (4.8)
 Employment status, n (%)
  In paid employment or self-employed 48,674 (75.2) 134,628 (66.4) 46,746 (49.2) 11,612 (46.3)
  Retired 11,970 (18.5) 56,500 (27.9) 40,443 (42.6) 9862 (39.3)
  Looking after home and/or family 2194 (3.4) 5578 (2.8) 2701 (2.8) 681 (2.7)
  Unable to work because of sickness or disability 722 (1.1) 2180 (1.1) 2310 (2.4) 1605 (6.4)
  Unemployed 662 (1.0) 2435 (1.2) 2117 (2.2) 1089 (4.3)
  Doing unpaid or voluntary work 344 (0.5) 907 (0.5) 378 (0.4) 117 (0.5)
  Full-time or part-time student 203 (0.3) 522 (0.3) 256 (0.3) 112 (0.5)
 Ethnicity, n (%)
  White 60,997 (93.3) 193,700 (94.7) 90,686 (94.6) 23,229 (91.6)
  South Asian 1806 (2.8) 4095 (2.0) 1580 (1.7) 622 (2.5)
  Black 1072 (1.6) 2994 (1.5) 1935 (2.0) 854 (3.4)
  Chinese 267 (0.4) 721 (0.4) 312 (0.3) 108 (0.4)
  Mixed background / others 1232 (1.9) 2960 (1.5) 1364 (1.4) 555 (2.2)
 Smoking status, n (%)
  Never 41,168 (63.2) 118,540 (58.2) 50,242 (52.6) 12,551 (49.7)
  Previous 18,901 (29.0) 67,082 (32.9) 34,420 (36.0) 8815 (34.9)
  Current 5087 (7.8) 18,207 (8.9) 10,870 (11.4) 3889 (15.4)
Obesity-related markers
 BMI, mean (SD) 25.7 (4.2) 27.1 (4.5) 28.2 (4.8) 28.89 (5.4)
 BMI categories, n (%)
  Underweight (< 18.5) 566 (0.9) 952 (0.5) 280 (0.3) 107 (0.4)
  Normal weight (18.5–24.9) 31,288 (48.1) 70,487 (34.6) 24,335 (25.5) 5781 (23.0)
  Overweight (25.0 to 29.9) 24,428 (37.5) 88,950 (43.7) 42,855 (44.9) 10,374 (41.3)
  Obese (≥30.0) 8788 (13.5) 43,274 (21.3) 27,941 (29.3) 8875 (35.3)
 Waist circumference (cm), mean (SD) 85.3 (12.3) 89.2 (12.9) 92.2 (13.3) 94.38 (14.2)
 Central Obesity, n (%) 13,362 (20.5) 60,575 (29.7) 37,674 (39.4) 11,327 (44.9)
 % Body fat, mean (SD) 29.2 (8.3) 30.8 (8.4) 32.7 (8.4) 32.89 (8.9)
Fitness, Physical activity and Sleep, mean (SD)
 Fitness (METs) 9.7 (3.5) 9.2 (3.4) 8.3 (3.3) 8.3 (3.5)
 Grip strength (kg) 31.1 (10.7) 31.5 (11.0) 30.4 (11.2) 30.5 (11.3)
 Total physical activity (MET.h.week−1) 6.6 (8.9) 6.7 (9.2) 6.3 (9.1) 5.0 (7.8)
 TV viewing (h.day−1) 0.7 (0.4) 2.3 (0.7) 4.1 (0.9) 5.3 (2.4)
 PC screen time (h.day−1) 0.8 (0.4) 1.0 (0.8) 1.3 (1.4) 3.0 (3.1)
 Screen time (h.day− 1) 1.6 (0.6) 3.4 (0.9) 5.4 (1.2) 8.2 (2.0)
 Sleep duration (h.day−1) 7.1 (0.9) 7.1 (1.0) 7.2 (1.1) 7.1 (1.2)
Dietary intake, mean (SD)
 Total energy (kcal.day−1) 2124.2 (636.5) 2115.3 (634.9) 2111.3 (660.9) 2126.5 (736.9)
 Protein intake (% of TE) 15.3 (3.4) 15.6 (3.6) 15.7 (3.8) 15.6 (4.0)
 Carbohydrates intake (% of TE) 47.7 (8.1) 47.1 (8.1) 47.0 (8.2) 46.9 (8.6)
 Total Fat intake (% of TE) 31.9 (6.6) 32.0 (6.7) 32.2 (6.8) 32.4 (7.1)
 Saturated intake (% of TE) 12.2 (3.3) 12.3 (3.3) 12.4 (3.4) 12.5 (3.5)
 Sugar intake (% of TE) 22.8 (6.9) 22.4 (6.9) 22.3 (7.1) 22.2 (7.5)
 Alcohol intake (% of TE) 5.1 (6.2) 5.3 (6.4) 5.2 (6.7) 5.0 (7.0)
 Red meat intake (portions.week−1) 1.8 (1.4) 1.9 (1.4) 2.0 (1.5) 2.1 (1.7)
 Processed meat intake (portions.week−1) 1.7 (1.1) 1.9 (1.1) 2.0 (1.1) 2.0 (1.1)
 Vegetable and Fruit intake (grams.day−1) 350.7 (196.9) 331.3 (189.1) 316.7 (192.7) 308.8 (213.5)
 Oily fish (portions.week−1) 1.1 (1.1) 1.1 (1.0) 1.1 (1.0) 1.0 (1.1)
Health status
 Diabetes history, n (%) 1784 (2.7) 7493 (3.7) 5411 (5.7) 2097 (8.3)
 High blood pressure history, n (%) 11,565 (17.7) 47,541 (23.3) 28,760 (30.1) 8281 (32.8)
 Systolic blood pressure (mmHg), mean (SD) 135.7 (19.4) 139.6 (19.5) 142.6 (19.5) 141.6 (19.8)
 Diastolic blood pressure (mmHg), mean (SD) 80.6 (10.7) 82.4 (10.6) 83.5 (10.5) 83.6 (10.8)
 Medication for cholesterol or blood pressure, n (%)
  None of the above 60,310 (92.3) 184,387 (90.2) 82,102 (85.6) 21,719 (85.6)
  Cholesterol-lowering medication 2259 (3.5) 9644 (4.7) 7267 (7.6) 2037 (8.0)
  Blood pressure medication 2805 (4.3) 10,439 (5.1) 6508 (6.8) 1612 (6.4)
  1. BMI body mass index, MET metabolic equivalent, SD standard deviation, TE total energy intake