TABLE 1

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

StudyStrataStudy and year of publicationStudy location
(language of publication)
Altitude MASLPatient group adults versus childrenSubjects
(subgroup)
Outcome measure included in analysisObserved changeMean differenceSMDTreatment duration and additional commentsQuality of evidence
11Dubiley and Shogentsukova, 1973 (1) [18]USSR
(Russian)
2000Adults
(21–52)
45
(mild asthma)
FEV1/VC71.9±7.4
to
88.4±2.7
+16.5+2.968 weeks; standard deviation recalculated from reported standard errorLow
2Dubiley and Shogentsukova, 1973 (2) [18]USSR
(Russian)
2000Adults
(21–52)
70
(moderate asthma)
FEV1/VC68.7±10.0
to
80.4±3.3
+11.7+1.57
3Dubiley and Shogentsukova, 1973 (3) [18]USSR
(Russian)
2000Adults
(21–52)
35
(severe asthma)
FEV1/VC64.0±5.3
to
71.4±7.1
+7.4+1.18
24Kolesar et al., 1977 [19]Czechoslovakia
(Slovak)
1800Adults
(27–39)
15FEV1 % pred67.1±6.6
to
69.9±7.3
+2.8+0.402 weeks; data extracted from a graphical presentationVery low
35Boner et al., 1985 [20]Italy
(English)
1756Children
(7–14)
14FEV1 % pred65.4±10.8
to
82.5±17.2
+17.1+1.198 weeksVery low
46Bobokhodzhaev and Shirinskii, 1990 (1) [21]USSR
(Russian)
1960Adults
(21–56)
20
(atopic asthma)
FEV1/VC54.3±10.3
to
63.2±17.4
+8.9+0.624 weeksLow
7Bobokhodzhaev and Shirinskii, 1990 (2) [21]USSR
(Russian)
1960Adults
(21–56)
24
(nonatopic asthma)
FEV1/VC54.1±10.3
to
75.1±23.5
+21+1.16
58Brimkulov, 1991 (1) [22]USSR
(Russian)
3200Adults
(18–58)
38
(mild asthma)
FEV1 % pred74.9±5.5
to
86.4±7.4
+11.5+1.764 weeks; standard deviation recalculated from reported standard errorHigh
9Brimkulov, 1991 (2) [22]USSR
(Russian)
3200Adults
(18–58)
94
(moderate asthma)
FEV1 % pred64.5±17.2
to
73.3±18.0
+8.8+0.50
610Piacentini et al., 1993 [23]#Italy
(English)
1756Children
(10.6±1.7)
20FEV1 % pred98.0±24.0
to
103.0±34.0
+5.0+0.172 weeks; data extracted from a graphical presentationLow
711Simon et al., 1994 [24]Switzerland
(English)
1560Children
(8–15)
14FEV1 % pred95.7±9.7
to
104.0±14.7
+8.3+0.675 weeksLow
812Allegra et al., 1995 [11]Italy and Nepal
(English)
4559 and 5050Adults
(23–48)
11FEV1 % pred102.7±20.4
to
104.8±20.1
+2.1+0.101 weekLow
913Boner et al., 1995 (1) [25]Italy
(English)
1756Children
(6–14)
13
(patients on budesonide)
FEV1 % pred89.9±9.9
to
99.5±10.7
+9.6+0.936 weeksLow
14Boner et al., 1995 (2) [25]Italy
(English)
1756Children
(6–14)
7
(patients on placebo)
FEV1 % pred92.9±6.5
to
95.0±9.7
+2.1+0.25
1015van Velzen et al., 1996 [12]Switzerland
(English)
1560Children
(10–18)
16FEV1 % pred92.1±23.2
to
97.0±20.4
+4.9+0.224 weeks; standard deviation recalculated from reported standard errorLow
1116Kokov, 1996 [26]Russian Federation
(Russian)
1850Children
(9–15)
68FEV1 % pred74.7±28.9
to
83.4±23.1
+8.7+0.333 weeks; standard deviation recalculated from reported standard error; study identified from www.elibrary.ruHigh
1217Valletta et al., 1997 [27]#Italy
(English)
1756Children
(9–13)
14FEV1 % pred82.0±16.0
to
85.0±14.0
+3.0+0.204 weeks; data extracted from a graphical presentationLow
1318Grootendorst et al., 2001 [28]Switzerland
(English)
1560Children
(12–18)
18FEV1 % pred85.6±18.9
to
94.8±17.6
+9.2+0.5010 weeks; standard deviation recalculated from reported standard errorLow
1419Peroni et al., 2002 [29]Italy
(English)
1756Children
(7–13)
18FEV1 % pred100.5±15.3
to
102.0±12.3
+1.5+0.1112 weeks; standard deviation recalculated from reported standard errorLow
1520Straub et al., 2004 [30]#Switzerland
(English)
1560Children
(4–14)
48FEV1 % pred105.1±15.9
to
107.0±18.0
+1.9+0.114 weeks; mean±sd recalculated from the reported median (95% CI)Moderate
1621Louie and Pare, 2004 [31]Nepal
(English)
4100Adults
(24±16)
5PEFR558±43
to
482±42
−76−1.792 weeksLow
1722Peroni et al., 2009 [32]Italy
(English)
1756Children
(7–14)
22FEV12.75±0.70
to
2.78±0.61
+0.03++0.054 weeks; standard deviation recalculated from reported standard errorLow
1823Huismans et al., 2010 [33]Nepal
(English)
6410Adults
(39±9)
24FEV1 % pred104.0±13.0
to
99.0±12.0
−5.0−0.404 weeksLow
1924Rijssenbeek-Nouwens et al., 2012 (1) [34]Switzerland
(English)
1560Adults
(41.5±14.5)
92
(sensitised to HDM)
FEV1 % pred88.4±20.4
to
94.2±20.1
+5.8+0.2912 weeksHigh
25Rijssenbeek-Nouwens et al., 2012 (2) [34]Switzerland
(English)
1560Adults
(48±15.3)
45
(nonsensitised to HDM)
FEV1 % pred86.5±26.2
to
92.8±23.1
+6.3+0.26
2026Seys et al., 2013 [35]Argentina
(English)
6965Adults
(39.6±11.3)
18FEV1 % pred90.2±12.0
to
98.0±14.0
+7.8+0.602 weeks; data extracted from a graphical presentationLow
2127Verkleij et al., 2013 (1) [14]#Switzerland
(English)
1560Children
(7–18)
51
(Netherlands Clinic Davos)
FEV1 % pred105.8±3.4
to
106.1±13.7
+0.3+0.036 weeksModerate
28Verkleij et al., 2013 (2) [14]#Switzerland
(English)
1560Children
(7–18)
48
(High Altitude Clinic Davos)
FEV1 % pred99.4±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.