Prevalence of acute mountain sickness in the Pyrenees

Abstract

Background: Acute mountain sickness (AMS) is the most common condition of High- Altitude Illnesses (HAI). The prevalence ranges between 15% and 80% depending on the

absolute altitude reached, speed of ascent, and individual susceptibility. However, there is a lack of information regarding AMS at moderate to high altitudes (2,500-3,500m); and, even less, in the Pyrenees. Objective: The main goals of the present study were to determinate the prevalence and risk factor for AMS in the Pyrenees. Methods: A cross-sectional study that includes mountaineers who have climbed a mountain with a height greater than 2,500m in the area of the Pyrenees. Between July and August 2019 data were collected using a questionnaire including sociodemographic, medical history and activity information. The diagnosis of AMS was based on the Lake Louise Score 2018 (LLS). Results: The study included 437 participants. One hundred and seventeen met diagnostic criteria of AMS, establishing a prevalence of 26.6% (95% confidence interval: 22.6% to 30.9%). The most common AMS symptom was headache, followed by fatigue or weakness, gastrointestinal symptoms and dizziness. Most of those affected by AMS had mild (88%) or moderate (12%) symptoms. In an adjusted multivariate analysis, heavy perceived exertion, bad physical condition and previous history of HAI were independent risk factors for AMS. Conclusions: One fourth of climbers in the Pyrenees experienced mild or moderate AMS. Previous history of HAI and other modifiable risk factors such as physical exertion and physical condition were strong predictors of AMS. Educational/informational programs for individuals planning climbing to high altitudes in the Pyrenees would be desirable