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Table 1 Characteristics of the studies included in the meta-analysis

From: Association between acute mountain sickness (AMS) and age: a meta-analysis

Study Max altitude (m) Male/Female (n) Sample size (n) LLS or CAS cut-off value Age range (mean, year) Age (year) P Subject origin Ascent mode Ascent duration
AMS Non-AMS Sum AMS No AMS
Hackett, 1976 [2] 4243 146 132 278 Arbitrary symptom score ≥ 2 18–71(33) 31.4 ± 9.7 35.2 ± 13.3 0.029 Britain, USA, France, Germany, Switzerland, Japan, Other Plane, Trek 4d
Wagner, 2006 [37] 4419 266/93 120 239 359 LLS ≥ 3 10–76(39.2) 34.40 ± 12.81 41.71 ± 14.71 < 0.0001 USA Trek 1–3 d
Mairer, 2009 [38] 3500 316/106 70 361 431 LLS ≥ 4 -- (37.4) 38.4 ± 11.1 37.2 ± 13.1 0.20 Austria Trek
Mairer (a), 2010 [39] 3454 64/11 30 45 75 LLS ≥ 4 -- (34.7) 35.1 ± 10.7 34.5 ± 10.2 0.79 Austria Trek
Mairer (b), 2010 [39] 3817 63/17 28 52 80 LLS ≥ 4 -- (36.8) 36.2 ± 12.2 38.1 ± 10.4 0.47 Austria Trek
Karinen, 2012 [40] 5600 34/22 24 12 36 LLS ≥ 3 24–45(32) 33 ± 7 30 ± 5 > 0.05 Finland Trek 7–17 d
Wei, 2012 [34] 4000 276 924 1200 CAS ≥ 5 20–50(35) 35.36 ± 19.54 35.80 ± 16.85 > 0.05 China
Mao, 2012 [35] 4768 135/87 71 213 284 LLS ≥ 3 18–69(40.5) 43.5 ± 13.5 37.8 ± 12.7 < 0.05 China Train 1.5 h
You, 2012 [41] 4300 314/0 119 195 314 LLS > 4 - (20.2) 20.08 ± 1.62 20.25 ± 1.83 0.414 China Bus 4 d
Harrison, 2013 [42] 3200 55/35 30 60 90 LLS ≥ 3 - (35.4) 33.8 ± 9.2 36.2 ± 9.4 > 0.05 USA Plane < 4 h
Song, 2014 [36] 3900 73/0 37 36 73 LLS ≥ 3 18–26(20.5) 20.72 ± 2.21 20.33 ± 2.05 > 0.05 China Car 5 d exposure
Wu, 2015 [44] 3886 102/77 80 99 179 LLS ≥ 3 11–13(11.8) 11.8 ± 0.5 11.8 ± 0.4 NS China Bus
Walk
6 h + 2 h
Bian, 2015 [45] 3700 150/ 84 66 150 LLS ≥ 3 18–60(22.2) 22.77 ± 3.83 21.39 ± 2.38 0.011 China Plane 2 h
Ren, 2015 [46] 4300 31/49 35 45 80 LLS > 3 20–50(38.4) 38.1 ± 11.8 38.6 ± 8.3 0.829 China Plane, bus 6 h
Li (a), 2015 [47] 3700 752/0 461 291 752 LLS ≥ 3 18–45(22.9) 23.0 ± 3.9 22.8 ± 3.9 0.475 China Plane 2.5 h
Li (b), 2015 [47] 4400 267/0 104 163 267 LLS ≥ 3 18–45(22.0) 22.2 ± 2.5 21.8 ± 2.3 0.162 China Car 3 h
Yu, 2016 [48] 3700 176/0 95 81 176 LLS ≥ 3 - (23.0) 23.21 ± 3.96 22.78 ± 3.45 0.181 China Plane 2 h
  1. AMS Acute mountain sickness, LLS Lake Louise score, CAS The Chinese AMS score, SD Standard deviation. -: No data or not mentioned