The prevalence of and risk factors for acute mountain sickness in the Eastern and Western Alps.

Acute mountain sickness (AMS) is the most common condition of high altitude illnesses. Its prevalence varies between 15% and 80% depending on the speed of ascent, absolute altitude reached, and individual susceptibility. Additionally, we assumed that the more experienced mountaineers of the Western Alps are less susceptible to developing AMS than recreational mountaineers of the Eastern Alps or tourist populations. Therefore, the main goals of the present study were the collection of data regarding the AMS prevalence and triggers in both the Eastern and Western Alps using identical methods. A total of 162 mountaineers, 79 in the Eastern Alps (3454 m) and 83 in the Western Alps (3817 m) were studied on the morning after their first night at high altitude. A diagnosis of AMS was based on a Lake Louise Score (LLS) ≥4, the presence of headache, and at least one additional symptom. Thirty of 79 subjects (38.0%) suffered from AMS at 3454 m in the Eastern Alps as did 29 of 83 (34.9%) at 3817 m in the Western Alps. After adjustment for altitude, the prevalence in the Western Alps constituted 24.5%, which differed significantly (p = 0.04) from that found in the Eastern Alps. The lower mountaineering experience of mountaineers in the Eastern Alps turned out to be the only factor for explaining their higher AMS prevalence. Thus, expert advice by mountain guides or experienced colleagues could help to reduce the AMS risk in these subjects.