Background

We previously showed that COPD patients can timely detect impending altitude-related adverse health effects (ARAHE) by structured self-monitoring (SSM) of symptoms and pulse oximetry (SpO2). In the current trial, we investigated whether acetazolamide therapy started in COPD patients testing SSM positive during altitude travel prevents ARAHE.

Methods

This randomized, placebo-controlled, double blind, parallel trial included COPD patients, FEV1 40-80%pred, SpO2≥92%, PaCO2<6kPa at altitude of residence (<800m). Patients traveled by bus to a clinic at 3100m and stayed there for 2 days. At 3100m, patients performed SSM (4 times/day). Those testing SSM positive (based on predefined symptoms and/or SpO2<85%) were randomized to subsequent placebo or acetazolamide (375mg/d) therapy. The incidence of ARAHE (primary outcome, defined as severe acute mountain sickness, SpO2<80% for >30min, or need of medical treatment for other reason) was observed during the further stay at 3100m. ClinicalTrials.gov NCT04913389.

Results

Of 241 COPD patients travelling to 3100m, 157 (72 women), mean±SD age 59±9y, FEV1 61±12%pred, turned SSM positive and were randomized. During the subsequent stay at 3100m, ARAHE occurred in 60 of 81 (74%) patients taking placebo and in 38 of 76 (50%) patients taking acetazolamide (P=0.002), number needed to treat 3.9 (95%CI 2.5 to 10.5); odds ratio 0.35 (95%CI 0.18 to 0.68). Acetazolamide was well tolerated, no serious adverse event occurred.

Conclusion

In lowlanders with COPD, travelling to 3100m, SSM-guided preventive acetazolamide therapy reduced the incidence of ARAHE. This novel approach may allow to restrict the use of preventive acetazolamide therapy to patients at risk.