Abstract
Introduction
Each year, millions of people travel to high altitude regions and are at risk for high altitude illness. Advances in transportation to these locations, including the construction of direct roadways and increased popularity of mountain sports, have contributed to the growing number of individuals at risk. Much of our current knowledge of high altitude illness is from studies conducted in the Himalayas, specifically in the Khumbu and Annapurna regions, and altitude mountain sickness (AMS) rates vary from as low as 16% to approaching 50%. We present the largest contemporary cross-sectional survey study involving trekkers in 2 trekking regions of the Nepal Himalaya.
Objective
To establish the prevalence of AMS in the Nepal Himalaya using a survey-based study of trekkers.
Methods
Study enrollment ran for approximately 6 wk during April and May 2022 in the villages of Lobuje and Manang along the popular Everest Base Camp Trek and Annapurna Circuit Trek, respectively. Any traveler who was spending their first night in the village could be included in the study. Participants were given a survey sheet that included demographic information and the Lake Louise Acute Mountain Sickness Score, which was completed both before bed on the first evening in each village and again upon waking in the morning the next day.
Results
This study enrolled 2983 participants from 91 countries. In Lobuche, there was a prevalence of AMS of 25.78% and a severe AMS prevalence of 4.55%. In Manang, there was an AMS prevalence of 14.89% and a severe AMS prevalence of 2.83%.
Conclusions
Our data represent the largest known dataset published to date on AMS. It establishes the contemporary prevalence of AMS along 2 routes in the Himalaya and supports the idea that the risk of AMS increases with altitude.
Keywords: altitude sickness, Nepal, wilderness medicine, prevalence, surveys and questionnaires