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. 2024 Sep 3;7(9):e2435253.
doi: 10.1001/jamanetworkopen.2024.35253.

Avalanche Survival Rates in Switzerland, 1981-2020

Simon Rauch  1   2 , Hermann Brugger  1   3 , Markus Falk  1 , Benjamin Zweifel  4 , Giacomo Strapazzon  1   3   5 , Roland Albrecht  6   7   8 , Urs Pietsch  6   7   8
Affiliations

Avalanche Survival Rates in Switzerland, 1981-2020

Simon Rauch et al. JAMA Netw Open. .

Abstract

Importance: Survival probability among individuals critically buried by avalanche is highly time dependent, which was demonstrated 30 years ago. However, it remains unclear whether avalanche survival probability has changed over time.

Objective: To assess the avalanche survival rate and probability as well as the rescue probability over the past 4 decades.

Design, setting, and participants: In this cohort study, avalanche data from Switzerland that were collected by the WSL Institute for Snow and Avalanche Research (SLF) in Davos were analyzed from the winter beginning in 1981 to that beginning in 2020 and compared with data from the period 1981 to 1990. Data were analyzed from January to April 2024.

Exposure: Critical avalanche burial (ie, burial involving the head and chest).

Main outcomes and measures: Survival rate among individuals critically buried by avalanche, survival probability, and rescue probability in relation to time buried under the avalanche.

Results: The study included 1643 individuals critically buried by avalanche (mean [SD] age, 37 [13.7] years; 1090 of 1342 with known sex [81.2%] were male) among 3805 avalanches involving 7059 persons. Compared with the period from 1981 to 1990, the total survival rate over the full study period increased from 43.5% (95% CI, 38.8%-48.3%) to 53.4% (95% CI, 51.0%-55.8%). Survival probability remained high at 91% (95% CI, 80%-100%) for rescue during the first 10 minutes but then decreased to 31% (95% CI, 11%-51%) for rescue between 10 and 30 minutes. The survival rate among those buried long term (>130 minutes) increased from 2.6% (95% CI, 0.7%-6.9%) to 7.3% (95% CI, 4.8%-10.7%). The median rescue time decreased from 45 (IQR, 15-148) minutes to 25 (IQR, 10-85) minutes. Survival rates among individuals rescued from avalanche by organized rescue teams increased from 14.0% (28 of 200) to 22.9% (161 of 704).

Conclusions and relevance: This cohort study of 1643 individuals critically buried by avalanche found that over the past 4 decades, total survival rates considerably increased and rescue times decreased. Survival rates among those buried long term (>130 minutes) also increased. These findings are likely attributable to collaborative efforts among stakeholders to enhance avalanche search-and-rescue techniques and medical interventions.

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Conflict of interest statement

Conflict of Interest Disclosures: None reported.

Figures

Figure 1.
Figure 1.. Flowchart of Avalanche Survivors and Nonsurvivors for Analysis
Figure 2.
Figure 2.. Survival Rates by Single Year, Running 3 Years, and Decade
Data points indicate single years; dark blue line, running 3 years; dashed blue line, decade; shading, 95% CIs. Vertical dotted lines represent decade cutoffs and the horizontal dotted line, the 50% case survival rate. The number of individuals was 416 between 1981 and 1990, 349 between 1991 and 2000, 469 between 2001 and 2010, and 409 between 2011 and 2020.
Figure 3.
Figure 3.. Cumulative Probability of Survival by Time Buried Under Avalanche in Minutes
Dark blue line represents new data from 1981 to 2020, with missing times imputed; orange line, data from 1981 to 1990 as used in the study by Falk et al, with missing times imputed; vertical dotted line, 15-minute reference mark.
Figure 4.
Figure 4.. Probability of Rescue by Rescue Type and Time Buried Under Avalanche in Minutes
Horizontal dotted line indicates rescue probability of 50%.
See this image and copyright information in PMC

References

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