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. 2016 Jun 6;2(2):00097-2015. doi: 10.1183/23120541.00097-2015

TABLE 1.

Characteristics of the 22 studies including 29 substrata included in the meta-analysis

Study Strata Study and year of publication Study location
(language of publication) 		Altitude MASL Patient group adults versus children Subjects
(subgroup) 		Outcome measure included in analysis Observed change Mean difference SMD Treatment duration and additional comments Quality of evidence
1 1 Dubiley and Shogentsukova, 1973 (1) [18] USSR
(Russian)		 2000 Adults
(21–52)		 45
(mild asthma)		 FEV1/VC 71.9±7.4
to
88.4±2.7		 +16.5 +2.96 8 weeks; standard deviation recalculated from reported standard error Low
2 Dubiley and Shogentsukova, 1973 (2) [18] USSR
(Russian)		 2000 Adults
(21–52)		 70
(moderate asthma)		 FEV1/VC 68.7±10.0
to
80.4±3.3		 +11.7 +1.57
3 Dubiley and Shogentsukova, 1973 (3) [18] USSR
(Russian)		 2000 Adults
(21–52)		 35
(severe asthma)		 FEV1/VC 64.0±5.3
to
71.4±7.1		 +7.4 +1.18
2 4 Kolesar et al., 1977 [19] Czechoslovakia
(Slovak)		 1800 Adults
(27–39)		 15 FEV1 % pred 67.1±6.6
to
69.9±7.3		 +2.8 +0.40 2 weeks; data extracted from a graphical presentation Very low
3 5 Boner et al., 1985 [20] Italy
(English)		 1756 Children
(7–14)		 14 FEV1 % pred 65.4±10.8
to
82.5±17.2		 +17.1 +1.19 8 weeks Very low
4 6 Bobokhodzhaev and Shirinskii, 1990 (1) [21] USSR
(Russian)		 1960 Adults
(21–56)		 20
(atopic asthma)		 FEV1/VC 54.3±10.3
to
63.2±17.4		 +8.9 +0.62 4 weeks Low
7 Bobokhodzhaev and Shirinskii, 1990 (2) [21] USSR
(Russian)		 1960 Adults
(21–56)		 24
(nonatopic asthma)		 FEV1/VC 54.1±10.3
to
75.1±23.5		 +21 +1.16
5 8 Brimkulov, 1991 (1) [22] USSR
(Russian)		 3200 Adults
(18–58)		 38
(mild asthma)		 FEV1 % pred 74.9±5.5
to
86.4±7.4		 +11.5 +1.76 4 weeks; standard deviation recalculated from reported standard error High
9 Brimkulov, 1991 (2) [22] USSR
(Russian)		 3200 Adults
(18–58)		 94
(moderate asthma)		 FEV1 % pred 64.5±17.2
to
73.3±18.0		 +8.8 +0.50
6 10 Piacentini et al., 1993 [23]# Italy
(English)		 1756 Children
(10.6±1.7)		 20 FEV1 % pred 98.0±24.0
to
103.0±34.0		 +5.0 +0.17 2 weeks; data extracted from a graphical presentation Low
7 11 Simon et al., 1994 [24] Switzerland
(English)		 1560 Children
(8–15)		 14 FEV1 % pred 95.7±9.7
to
104.0±14.7		 +8.3 +0.67 5 weeks Low
8 12 Allegra et al., 1995 [11] Italy and Nepal
(English)		 4559 and 5050 Adults
(23–48)		 11 FEV1 % pred 102.7±20.4
to
104.8±20.1		 +2.1 +0.10 1 week Low
9 13 Boner et al., 1995 (1) [25] Italy
(English)		 1756 Children
(6–14)		 13
(patients on budesonide)		 FEV1 % pred 89.9±9.9
to
99.5±10.7		 +9.6 +0.93 6 weeks Low
14 Boner et al., 1995 (2) [25] Italy
(English)		 1756 Children
(6–14)		 7
(patients on placebo)		 FEV1 % pred 92.9±6.5
to
95.0±9.7		 +2.1 +0.25
10 15 van Velzen et al., 1996 [12] Switzerland
(English)		 1560 Children
(10–18)		 16 FEV1 % pred 92.1±23.2
to
97.0±20.4		 +4.9 +0.22 4 weeks; standard deviation recalculated from reported standard error Low
11 16 Kokov, 1996 [26] Russian Federation
(Russian)		 1850 Children
(9–15)		 68 FEV1 % pred 74.7±28.9
to
83.4±23.1		 +8.7 +0.33 3 weeks; standard deviation recalculated from reported standard error; study identified from www.elibrary.ru High
12 17 Valletta et al., 1997 [27]# Italy
(English)		 1756 Children
(9–13)		 14 FEV1 % pred 82.0±16.0
to
85.0±14.0		 +3.0 +0.20 4 weeks; data extracted from a graphical presentation Low
13 18 Grootendorst et al., 2001 [28] Switzerland
(English)		 1560 Children
(12–18)		 18 FEV1 % pred 85.6±18.9
to
94.8±17.6		 +9.2 +0.50 10 weeks; standard deviation recalculated from reported standard error Low
14 19 Peroni et al., 2002 [29] Italy
(English)		 1756 Children
(7–13)		 18 FEV1 % pred 100.5±15.3
to
102.0±12.3		 +1.5 +0.11 12 weeks; standard deviation recalculated from reported standard error Low
15 20 Straub et al., 2004 [30]# Switzerland
(English)		 1560 Children
(4–14)		 48 FEV1 % pred 105.1±15.9
to
107.0±18.0		 +1.9 +0.11 4 weeks; mean±sd recalculated from the reported median (95% CI) Moderate
16 21 Louie and Pare, 2004 [31] Nepal
(English)		 4100 Adults
(24±16)		 5 PEFR 558±43
to
482±42		 −76 −1.79 2 weeks Low
17 22 Peroni et al., 2009 [32] Italy
(English)		 1756 Children
(7–14)		 22 FEV1 2.75±0.70
to
2.78±0.61		 +0.03+ +0.05 4 weeks; standard deviation recalculated from reported standard error Low
18 23 Huismans et al., 2010 [33] Nepal
(English)		 6410 Adults
(39±9)		 24 FEV1 % pred 104.0±13.0
to
99.0±12.0		 −5.0 −0.40 4 weeks Low
19 24 Rijssenbeek-Nouwens et al., 2012 (1) [34] Switzerland
(English)		 1560 Adults
(41.5±14.5)		 92
(sensitised to HDM)		 FEV1 % pred 88.4±20.4
to
94.2±20.1		 +5.8 +0.29 12 weeks High
25 Rijssenbeek-Nouwens et al., 2012 (2) [34] Switzerland
(English)		 1560 Adults
(48±15.3)		 45
(nonsensitised to HDM)		 FEV1 % pred 86.5±26.2
to
92.8±23.1		 +6.3 +0.26
20 26 Seys et al., 2013 [35] Argentina
(English)		 6965 Adults
(39.6±11.3)		 18 FEV1 % pred 90.2±12.0
to
98.0±14.0		 +7.8 +0.60 2 weeks; data extracted from a graphical presentation Low
21 27 Verkleij et al., 2013 (1) [14]# Switzerland
(English)		 1560 Children
(7–18)		 51
(Netherlands Clinic Davos)		 FEV1 % pred 105.8±3.4
to
106.1±13.7		 +0.3 +0.03 6 weeks Moderate
28 Verkleij et al., 2013 (2) [14]# Switzerland
(English)		 1560 Children
(7–18)		 48
(High Altitude Clinic Davos)		 FEV1 % pred 99.4±14.0
to
99.7±15.5		 +0.3 +0.02

Data are presented as n, range, mean±sd or %, unless otherwise stated. MASL: metres above sea level; SMD: standardised mean difference; FEV1: forced expiratory volume in 1 s; VC: vital capacity; PEFR: peak expiratory flow rate; HDM: house dust mite. #: study without baseline lung function at sea level, only at first arrival at altitude; : L·min−1; +: L.