Prevalence of acute mountain sickness on Mount Fuji: A pilot study

Abstract

Background: Few studies have investigated climbing-related acute mountain sickness (AMS) on Mt Fuji. Although several studies of AMS have been conducted elsewhere, Mt Fuji is unique because there are many mountain lodges between the fifth station (a common starting point for climbers at an altitude of 2305 m) and the summit (3776 m), and many climbers commonly sleep overnight at mountain lodges during their ascents. This study surveyed the prevalence of AMS among climbers on Mt Fuji to determine which factors, if any, were related to the risk of developing AMS.

Methods: This study collected data from 345 participants who climbed Mt Fuji in August 2013, including information regarding age, sex, climbing experience and whether the climber stayed at a mountain lodge (n = 239). AMS was surveyed using the Lake Louise Score (LLS) questionnaire. The item on perceived sleep quality was excluded for those who did not stay at a mountain lodge (n = 106).

Results: The overall prevalence of AMS was 29.5% (≥ 3 LLS with headache). According to a univariate analysis, AMS was not associated with sex (male vs female), age group (20-29, 30-39, 40-49 or >50 years) or stay at a mountain lodge (single day vs overnight stay). Conversely, prior experience climbing Mt Fuji (no prior attempts vs one or more prior attempts) was related to the risk of AMS. In addition, there was a significant deviation in the number of participants reporting poor sleep, and total sleep time was significantly shorter in participants with AMS.

Conclusions: These preliminary findings suggest that no single factor can explain the risk for developing AMS while climbing Mt Fuji. In addition, impaired perceived sleep quality was associated with the severity of AMS in climbers who stayed overnight at a mountain lodge.

Keywords: Climbing experience; exposure time; overnight stay; sleep disturbance.