Acute mountain sickness among tourists visiting the high-altitude city of Lhasa at 3658 m above sea level: a cross-sectional study

Abstract

BackgroundTraveling to Tibet implies a risk for developing acute mountain sickness (AMS), and the size of this problem is likely increasing due to the rising number of tourists. No previous study on AMS has been conducted among the general tourist population in Tibet. Thus, the aim of this study was to estimate the prevalence and determinants of AMS in a large tourist population visiting Lhasa.MethodsA sample of 2385 tourists was recruited from seven randomly selected hotels in Lhasa between June and October 2010. Within three days of their first arrival, the participants filled in a questionnaire based on the Lake Louise Scoring System (LLSS) about AMS-related symptoms and potential contributing factors. AMS was defined as the presence of headache and a cumulative Lake Louise Score ≥4. After estimating the prevalence of AMS, a Log-Binomial Model was applied to analyse the relationship between AMS and selected risk factors.ResultsThe prevalence of AMS was 36.7 % (95 % CI: 34.6–38.7 %) and was not dependent on tourists’ country of origin. Among the participants who developed AMS, 47.6 % reported that they experienced symptoms within the first 12 h after arriving in Lhasa, and 79.0 % reported that they had to reduce their activity level. A poor or average health condition (adjusted PR 1.63, 95 % CI 1.38–1.93), an age below 55 years (adjusted PR 1.29, 95 % CI 1.04–1.60), a rapid ascent to Lhasa (adjusted PR 1.17, 95 % CI 1.02–1.34) were independent AMS risk factors, while smoking (adjusted PR 0.75, 95 % CI 0.59–0.96) and pre-exposure to high altitude (adjusted PR 0.71, 95 % CI 0.60–0.84) reduced the risk of AMS.ConclusionsAMS is commonly experienced by tourists visiting Lhasa Tibet, and often affects their activities. The tourists’ country of origin did not seem to affect their risk of AMS, and their age was inversely related to AMS. Subjects planning to visit a high-altitude area should be prepared for experiencing AMS-related problems, and consider preventive measures such as pre-exposure or a gradual ascent to high altitudes.

Does This Patient Have Acute Mountain Sickness?

“…[16][17][18] The risk for AMS is as much as 2.06-fold (95% CI, 1.15-3.72) lower for people older than 50 years. 12,14,[19][20][21][22] Women may be more likely affected than men, 19,22,23 but this finding is not consistent. 11,13,14,24 Medical conditions such as migraine, 10,11,25 obesity, 22,26 and mood states (anxiety) might also play a role in the development of AMS, 27 whereas smoking and alcohol consumption do not appear to increase the risk for AMS.…”

“…3,20,28 The most important modifiable behaviors at altitude that can influence the risk of developing AMS are the altitude attained and speed of ascent. 9,11,15,20 Ascents that are faster than 400 m per day (1300 ft/d) have an OR of 4.69 (95% CI, 2.79-7.90), whereas slower ascents have an OR of 0.30 (95% CI, 0.20-0.44) for the development of AMS. AMS is less likely to develop when there has been preacclimatization (ie, previous exposure to altitude within 1-2 months) 9,14,19,20 or medical prophylaxis with acetazolamide or dexamethasone.…”

“…[29][30][31] In contrast, physical training does not reduce the risk for developing AMS. 11,12,15,20,26,32 There are no biomedical tests that can establish a diagnosis of AMS; consequently, the diagnosis is made from clinical features. AMS is characterized by subjective symptoms (headache, anorexia, nausea, sometimes vomiting, dizziness, fatigue, and sleep disturbances) and, less frequently, few objective clinical signs (ataxia, palpitations, pulmonary rales, cyanosis) reported by the affected individual or through observations made by travel companions of persons with AMS.…”

STAT3-RXR-Nrf2 activates systemic redox and energy homeostasis upon steep decline in pO2 gradient

“…Most of the previous studies have focused on the temporal effects of a sample set at a particular altitude regarding acclimatization with most authors discouraging a high rate of ascent [18] , [19] , [20] . Some articles have also discussed the ascent of similar climbers in similar mountain ranges but at different ascent rates with suggestions for identification of susceptible and prophylaxis [21] , [22] , [23] , [24] , [25] . But the perturbations in redox and energy homeostasis at various altitude zones have not been investigated.…”

Deciphering Molecular Cascades in a Novel Acclimatization Strategy for Rapid Ascent to High Altitude

“…Most of the previous studies have focused on the temporal effects of a sample set at a particular altitude regarding acclimatization with most authors discouraging a high rate of ascent[10–12]. Some articles have also discussed the ascent of similar climbers in similar mountain ranges but at different ascent rates with suggestions for identification of susceptible and prophylaxis[13–17]. But the process of acclimatization remains untouched in all the articles cited above let alone any suggestions regarding rapid acclimatization.…”