Fatalities in High Altitude Mountaineering: A Review of Quantitative Risk Estimates

Abstract

Quantitative estimates for mortality in high altitude mountaineering are reviewed. Special emphasis is placed on the heterogeneity of the risk estimates and on confounding. Crude estimates for mortality are on the order of 1/1000 to 40/1000 persons above base camp, for both expedition members and high altitude porters. High altitude porters have mostly a lower risk than expedition members (risk ratio for all Nepalese peaks requiring an expedition permit: 0.73; 95 % confidence interval 0.59-0.89). The summit bid is generally the most dangerous part of an expedition for members, whereas most high altitude porters die during route preparation. On 8000 m peaks, the mortality during descent from summit varies between 4/1000 and 134/1000 summiteers (members plus porters). The risk estimates are confounded by human and environmental factors. Information on confounding by gender and age is contradictory and requires further work. There are indications for safety segregation of men and women, with women being more risk averse than men. Citizenship appears to be a significant confounder. Prior high altitude mountaineering experience in Nepal has no protective effect. Commercial expeditions in the Nepalese Himalayas have a lower mortality than traditional expeditions, though after controlling for confounding, the difference is not statistically significant. The overall mortality is increasing with increasing peak altitude for expedition members but not for high altitude porters. In the Nepalese Himalayas and in Alaska, a significant decrease of mortality with calendar year was observed. A few suggestions for further work are made at the end of the article.

Mountaineers on Mount Everest: Effects of age, sex, experience, and crowding on rates of success and death

“…Comparable trends are evident in analyses of climbers on other Nepalese and border peaks [7], as well as on Denali, Alaska (6194 m) [18]. Nevertheless, gender percentages on high peaks are still far from parity [10].…”

“…Retrospective data do not permit a causal analysis of these historical shifts, which are confounded by many factors [6,10]. Even so, the shift in sex ratio on Everest and other high peaks [7,18] likely mirrors the increased participation by women in many sports in recent decades [19].…”

“…Several studies have used HD to evaluate mountaineering successes and its risks [5][6][7][8][9][10] (additional references are listed on the HD website). For example, we [11] previously analyzed relationships of age and of sex on rates of "success" (= reached summit), of "complete success" (summited and returned safely to base camp), and of death of mountaineers on Everest.…”

Amputation Risk Factors in Severely Frostbitten Patients

“…Prior observations regarding risk and mountaineering experience indicate that climbing experience at high altitude does not have a positive influence on mortality. Furthermore, there is a positive association between mortality and the number of expeditions at high altitude [19,20]. In the case of avalanche accidents, an increase in mortality due to the repeated exposure to the hostile environment has been observed among more experienced and skilled subjects [21].…”

Successful climbing to extreme altitude is a hairy venture

“…() provide evidence indicating that a high baseline density of hair‐like thin blood vessels before leaving on an altitude climbing expedition increases the chances of reaching the summit of a 7126 m high Himalayan peak. Because climbing to such extreme altitudes is dangerous, with crude estimates of mortality ranging between 1 in 1000 to 40 in 1000 persons venturing above base camp (Weinbruch & Nordby, ), it would seem justified to conclude that climbing in the Himalaya is indeed a hairy activity.…”