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Table 1 Study and participant characteristics

From: Tracking of total sedentary time and sedentary patterns in youth: a pooled analysis using the International Children’s Accelerometry Database (ICAD)

  Wave ALSPAC EYHS Denmark EYHS Portugal HEAPS IBDS PEACH SPEEDY CLANa
Country   UK Denmark Portugal Australia US UK UK Australia
Number of waves   2 waves 2 waves 2 waves 2 waves 4 waves 2 waves 3 waves 3 waves
Average follow-up duration (years) W1-W2 2.1 ± 0.3 6.0 ± 0.3 7.2 ± 0.2 3.1 ± 0.2 2.9 ± 0.5 1.1 ± 0.1 1.0 ± 0.04 3.0 ± 0.06
W1-W3      5.4 ± 0.5   4.1 ± 0.1 4.9 ± 0.2
W1-W4      7.4 ± 0.5    
Data-collection period W1 All months 2003–2005 All months 1997–1998 January – June 2000 February – December 2002–2003 September –November 1998–2000 January – November 2006–2008 February – July 2007 March–December 2001
W2 All months 2005–2007 All months 2003–2004 January – July 2007–2008 May – December September –November 2000–2004 All, 2007–2009 March – July 2008 July – November 2004
W3      September –November 2003–2005   April–September 2011 May–November 2006
W4      September–December 2005–2007    
Number of participants with baseline accelerometer data / valid baseline accelerometer data W1 6085 / 5455 529 / 283 1218 / 631 1389 / 1040 437 / 329 1269 / 816 2009 / 1708 1162 / 1022
Number of participants included in analysis W1 2992 122 33 226 306 386 663 428
W2 2992 122 33 226 227 386 565 361
W3      267   275 324
W4      213    
Gender (% boys) W1 46.6 41.0 36.4 51.8 46.4 39.9 43.4 46.3
Mean age and range (years) W1 11.7 ± 0.2 (10.6–13.6) 9.6 ± 0.4 (8.6–10.5) 9.7 ± 0.3 (9.1–10.4) 8.1 ± 2.6 (5.0–12.6) 5.6 ± 0.5 (4.7–7.5) 10.9 ± 0.4 (10.1–11.8) 10.2 ± 0.3 (9.5–10.8) 9.5 ± 2.7 (5.5–15.0)
W2 13.8 ± 0.2 (12.6–14.8) 15.7 ± 0.4 (14.9–16.8) 16.9 ± 0.31 (16.3–17.5) 11.2 ± 2.6 (8.1–15.9) 8.6 ± 0.5 (7.6–10.7) 12.0 ± 0.4 (11.1–12.8) 10.8 ± 0.4 (10.0–12.0)b 12.5 ± 2.7 (8.5–15.9)
W3      11.1 ± 0.3 (10.6–12.7)   14.3 ± 0.3 (13.7–14.9) 14.1 ± 2.6 (10.5–17.7)
W4      13.0 ± 0.3 (12.5–14.4)    
BMI z-score W1 0.31 ± 1.16 0.19 ± 0.98 0.44 ± 1.33 0.69 ± 0.98 0.37 ± 1.06 0.29 ± 1.17 0.37 ± 1.16 0.60 ± 1.04
W2 0.20 ± 1.09 0.08 ± 0.86 0.22 ± 0.99 0.62 ± 0.99 0.65 ± 1.31 0.30 ± 1.17 NA. 0.60 ± 1.07
W3      0.73 ± 1.31   0.25 ± 1.20 0.54 ± 1.04
W4      0.65 ± 1.28    
Total sedentary time (minutes/day) W1 370 ± 68 333 ± 101 366 ± 116 282 ± 73 246 ± 49 387 ± 64 371 ± 64 316 ± 79
W2 425 ± 76 492 ± 72 544 ± 78 388 ± 96 318 ± 57 414 ± 69 391 ± 65 381 ± 92
W3      356 ± 65   475 ± 73 446 ± 104
W4      413 ± 73    
Prolonged sedentary time (minutes/day) W1 158 ± 62 143 ± 103 183 ± 134 102 ± 45 81 ± 36 177 ± 61 172 ± 61 122 ± 57
W2 209 ± 78 272 ± 90 366 ± 97 176 ± 90 118 ± 49 196 ± 63 191 ± 64 172 ± 79
W3      148 ± 56   269 ± 81 237 ± 110
W4      203 ± 73    
Day-to-day variation in total sedentary time (minutes/day) W1 54 ± 19 53 ± 21 50 ± 24 48 ± 19 41 ± 19 55 ± 21 54 ± 21 51 ± 22
W2 60 ± 22 68 ± 27 74 ± 37 56 ± 21 47 ± 21 60 ± 22 55 ± 19 57 ± 22
W3      51 ± 22   64 ± 25 63 ± 27
W4      57 ± 25    
Day-to-day variation in prolonged sedentary time (minutes/day) W1 47 ± 19 45 ± 24 44 ± 23 40 ± 20 32 ± 17 48 ± 19 48 ± 20 43 ± 22
W2 55 ± 23 63 ± 28 84 ± 34 51 ± 23 38 ± 20 53 ± 21 53 ± 20 52 ± 24
W3      43 ± 20   63 ± 23 61 ± 30
W4      57 ± 23    
MVPAc (minutes/day)
(median with (interquartile range))
W1 30 (24) 23 (25) 19 (33) 38 (28) 25 (18) 21 (17) 25 (21) 35 (23)
W2 30 (26) 17 (20) 23 (22) 26 (23) 31 (24) 23 (20) 23 (21) 39 (30)
W3      26 (26)   20 (21) 29 (24)
W4      22 (24)    
Accelerometer wear time (minutes/day) W1 792 ± 52 776 ± 56 783 ± 72 755 ± 64 768 ± 43 769 ± 60 773 ± 57 782 ± 65
W2 792 ± 62 831 ± 56 820 ± 78 778 ± 66 786 ± 44 786 ± 70 773 ± 61 796 ± 65
W3      783 ± 43   796 ± 63 803 ± 66
W4      790 ± 57    
  1. Data are reported as means ± standard deviations, unless otherwise stated. a Baseline wave was called CLASS; b calculated from self-reported age in years; c data for MVPA was not normally distributed and is reported as median with (interquartile range)