This is a randomized, placebo-controlled, double-blind parallel trial evaluating the efficacy of acetazolamide prophylaxis in reducing the incidence of altitude related adverse health effects (ARAHE) in lowlanders with chronic obstructive pulmonary disease travelling to altitude. Participants living in the Bishkek area, Kyrgyzstan (760m), will be transferred by car within 4h to the Tuja Ashu high altitude clinic (3200 m), and stay there for 2 days. Acetazolamide 375mg/day (or placebo), will be administered before departure at 760 m and during the stay at altitude. Outcomes will be assessed during the stay at 3200 m.
An interim analysis will be carried out when 90 patients will have completed the study or after the first year. The Peto's method will be used to correct the P-values.
