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Table 1 Extracted data characteristics

From: Association between smoking and the risk of acute mountain sickness: a meta-analysis of observational studies

Research Altitude (m) Sample size AMS Normal Diagnosis of AMS with cut-off value Age (mean) BMI (mean) Sex (m/f)
Smoking Non-smoking Smoking Non-smoking Smoking Non-smoking AMS Normal AMS Normal AMS Normal
Ren, 2015 [14] 4300 16 64 3 32 13 32 LLS > 3 38.1 38.6 24.7 26.2 9/26 22/23
Wu, 2012 [17] 4525 182 200 71 102 111 98 LLS >3 OR LLS >4       
You, 2012 [19] 4300 138 176 36 83 102 93 LLS > 4 20.08 20.25 21.31 21.47 119/0 195/0
MacInnis, 2013 [26] 4380 147 344 42 125 105 219 LLS ≥ 3      100/67 244/80
Mairer, 2010(a) [28] 3454 9 66 4 26 5 40 LLS ≥ 4 35.1 34.5 23.4 23.3 25/5 39/6
Mairer, 2010(b) [28] 3817 13 67 3 25 10 42 36.2 38.1 23.5 22.8 22/6 41/11
Mairer, 2009 [27] 3500 61 370 12 58 49 312 LLS ≥ 4 38.4 37.2 23.7 23.3 50/20 266/86
Schneider, 2002(a) [4] 4559 56 331 16 103 40 228 ESQ ≥ 0.70 38.2 22.6 314/73
Schneider, 2002(b) [4] 4559 72 368 21 99 51 269 37.0 22.7 359/81
  1. Mairer (2010) [28] reported two studies (2010a and 2010b) that were independent. Schneider (2002) [4] also published two studies (2002a and 2002b) that were independent. Schneider (2002) [4] used the Environmental Symptom Questionnaire (ESQ) to diagnose AMS using an ESQ cut-off value of 0.70, which corresponded to a Lake Louise Score (LLS) of 4. Wu (2012) [17] did not provide original data regarding age, gender or BMI. MacInnis (2013) [26] did not provide clear data regarding age or BMI. Schneider (2002) [4] provided only data regarding the total population of subjects. In addition, we analyzed how the studies defined smoking and found that only one article (Wu (2012) [17]) provided the following clear definition of smoking: “A smoker was someone who smoked 10 or more cigarettes/day for >6 months”