title: High-altitude alpine therapy and lung function in asthma: systematic review and meta-analysis.
abstract: We used meta-analysis to measure the effect of high-altitude climate therapy (HACT) on lung function outcomes in asthma, and systematically searched PubMed, Embase and www.elibrary.ru for publications appearing from 1970 to mid-2015. We included studies carried out with children or adults with an exposure of up to 12 weeks at an altitude of ≥1500 m above sea level. Changes in forced expiratory volume in 1 s (FEV1), FEV1/vital capacity ratio or peak expiratory flow rate as the HACT intervention outcomes were analysed. We included data for 907 participants (age range 4-58 years) from 21 studies, altogether including 28 substrata based on asthma type or severity. Only three of 21 included studies had high quality, whereas 93% of substudies reported lung function improvement with an overall pooled standardised mean difference (SMD) of 0.53 (95% CI 0.43-0.62). The measured effect of HACT was greater in adults (SMD 0.75, 95% CI 0.63-0.88, n=14) than in children (SMD 0.24, 95% CI 0.09-0.38, n=14). Studies at altitude >2000 m above sea level yielded the same effect as those at lower altitude. Based on a cut-point of a 0.50 change in SMD to define a meaningful clinical difference, HACT appears to have efficacy as an intervention. This extent of benefit appears to be limited to adults with asthma.
authors.affiliation: Dept of Internal Medicine, Occupational Diseases and Hematology, Kyrgyz State Medical Academy, Bishkek, Kyrgyz Republic.
authors.forename: Denis
authors.initials: D
authors.lastname: Vinnikov
authors.affiliation: Division of Occupational and Environmental Medicine, University of California San Francisco, San Francisco, CA, USA; Community Medicine and Pilgrims Healthcare Dept, Umm Al-Qura University College of Medicine, Mecca, Saudi Arabia.
authors.forename: Abdullah
authors.initials: A
authors.lastname: Khafagy
authors.affiliation: Division of Occupational and Environmental Medicine, University of California San Francisco, San Francisco, CA, USA.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Blanc
authors.affiliation: Dept of Internal Medicine, Occupational Diseases and Hematology, Kyrgyz State Medical Academy, Bishkek, Kyrgyz Republic.
authors.forename: Nurlan
authors.initials: N
authors.lastname: Brimkulov
authors.affiliation: School of Public Health, University of California Berkeley, Berkeley, CA, USA.
authors.forename: Craig
authors.initials: C
authors.lastname: Steinmaus