Asthma rehabilitation at high vs. low altitude: randomized parallel-group trial

BACKGROUND: To investigate the effect of asthma rehabilitation at high altitude (3100 m, HA) compared to low altitude (760 m, LA). METHODS: For this randomized parallel-group trial insufficiently controlled asthmatics (Asthma Control Questionnaire (ACQ) > 0.75) were randomly assigned to 3-week in-hospital rehabilitation comprising education, physical-&breathing-exercises at LA or HA. Co-primary outcomes assessed at 760 m were between group changes in peak expiratory flow (PEF)-variability, and ACQ) from baseline to end-rehabilitation and 3 months thereafter. RESULTS: 50 asthmatics were randomized [median (quartiles) LA: ACQ 2.7(1.7;3.2), PEF-variability 19%(14;33); HA: ACQ 2.0(1.6;3.0), PEF-variability 17%(12;32)]. The LA-group improved PEF-variability by median(95%CI) -7%(− 14 to 0, p = 0.033), ACQ − 1.4(− 2.2 to − 0.9, p < 0.001), and after 3 months by − 3%(− 18 to 2, p = 0.103) and − 0.9(− 1.3 to − 0.3, p = 0.002). The HA-group improved PEF-variability by − 10%(− 21 to − 3, p = 0.004), ACQ − 1.1(− 1.3 to − 0.7, p < 0.001), and after 3 months by − 9%(− 10 to − 3, p = 0.003) and − 0.2(− 0.9 to 0.4, p = 0.177). The additive effect of HA vs. LA directly after the rehabilitation on PEF-variability was − 6%(− 14 to 2), on ACQ 0.3(− 0.4 to 1.1) and after 3 months − 5%(− 14 to 5) respectively 0.4(− 0.4 to 1.1), all p = NS. CONCLUSION: Asthma rehabilitation is highly effective in improving asthma control in terms of PEF-variability and symptoms, both at LA and HA similarly. TRIAL REGISTRATION: Clinicaltrials.gov: NCT02741583, Registered April 18, 2016. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12890-019-0890-y) contains supplementary material, which is available to authorized users.