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| Journal of the New Zealand Medical Association,
04-July-2008, Vol 121 No 1277
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Risk and severity of injury in a population of BASE
jumpers
Erik Monasterio, Omer Mei-Dan
New Zealand has attracted an international reputation as an
adventure sport destination. Worldwide adventure tourism and adventure sports
are important leisure activities, of growing popularity. In this context,
commercial adventure tourism has become increasingly important to the New
Zealand economy. Adventure sports encompass a number of outdoor activities
including rock climbing, mountaineering, skydiving, white-water rafting,
mountain biking, and BASE jumping.
Recent reports in the literature have highlighted
significant risk of injury and death associated with mountaineering, skydiving,
white-water rafting, and mountain
biking.1–5
BASE jumping is a sport that developed out of skydiving and
uses specially adapted parachutes to jump from fixed objects. "BASE" is an
acronym that stands for the four categories of fixed objects that one can jump
off. These are: Building, Antenna,
Span (a bridge, arch, or dome) and Earth (a
cliff or other natural formation).
BASE jumping is an “extreme sport” and is ranked
as being amongst the most dangerous adventure sports in the world (Figure
1).6 As such, BASE jumping has been banned from
many popular launch sites such as the Eiffel Tower in Paris and in Yosemite
National Park (e.g. from El Capitan cliff where there has been fatalities) in
California.
BASE jumping is considered to be significantly more
dangerous than skydiving. As BASE jumps are made from lower altitudes than
skydives (often less than 500 feet above ground level), BASE jumpers generally
fall at lower speeds, have far less aerodynamic control, and may lose flying
stability.
If the parachute is deployed while the jumper is unstable
there is a high risk of entanglement or malfunction. The single canopy used may
also be facing the wrong direction. Such an off-heading opening is not
problematic in skydiving, but off-heading opening that results in object strike
is the leading cause of serious injury and death in BASE jumping. Also as BASE
jumping takes place in close proximity to a cliff or tower which provides the
jump platform, the BASE jumper may collide with the object.
Figure 1. BASE jumping examples
The only published study on morbidity and mortality
associated with this sport examined the frequency of injuries and death
associated with BASE jumping from a cliff in Norway and determined that BASE
jumping is associated with a five- to eightfold risk for death or injury,
compared with data on regular skydiving.7
Interpretation and application of this data is limited by the absence of
information on demographic characteristics or BASE jumper level of experience.
Furthermore the report findings relate to the outcome of jumps from a single
cliff, rather than the broad range of objects from which jumpers may
launch.
The purpose of this paper is to report the demographic
characteristics and morbidity findings in an international group of BASE
jumpers. The degree of risk has been estimated utilising accident rates as
denominator data and frequency of BASE jumps as numerator data. The data is
taken from a study that has also examined the psychological characteristics in
this population (Monasterio, Mei-Dan, and Mulder in preparation).
MethodVolunteers were recruited from BASE jump group
meetings, adventure website forums, and from personal communication among the
BASE jumping community. All volunteers who expressed an interest and contacted
the authors were recruited into the study.
After giving written consent, participants completed
several questionnaires providing demographic information and BASE jump
information (estimated number of base jumps per year, how long they had been
involved in the sport, whether they had had “near misses”, and
whether they had suffered base jumping accidents).
The Cloninger Temperament and Character Inventory was
also completed.8
Severity of accidents was rated as either:
ResultsDemographics—A total of 35 volunteers
completed the questionnaires. Only one volunteer who requested inclusion into
the study failed to return completed questionnaires. Thirty-four subjects (97%)
were male and the median age was 34 (range 21 to 55 years.). Nineteen subjects
(54%) were single/unmarried and most (27; 77%) did not have children. Fourteen
participants (40%) were from the North American continent, 13 (37%) from Europe,
6 (17%) from Oceania, and 2 (6%) from Israel.
Thirty-five (100%) of the participants were involved in
other adventure sports—the most common was skydiving involving all
participants (35; 100%) and rock climbing/alpinism (16; 41%) participants.
BASE jumper characteristics are summarised in Table
1.
Table 1. BASE jumper
characteristics
Med=Median.
The median time of participation in BASE jumping was 4 years
(0.25–17 years.), and the median number of jumps was 275 (7–1600).
All 4 objects were used as launching platforms, without any particular object
preference.
Participants estimated that the frequency of “near
misses” from jumping was 3% and injury was 0.5%. Interestingly, 26
subjects (74%) had witnessed the death of at least one jumper from BASE
jumping.
Accident findings are summarised
in Table 2.
Table 2. Accident characteristics of study
participants
An estimated 9914 jumps were made; 39 accidents were
reported, involving 21 (60%) of the participants. There was therefore 1 accident
for every 254 jumps—a 0.4% injury rate. There were 12 severe, 17 moderate,
and 10 mild accidents.
Of those who had more than one accident, nine participants
were involved in two separate accidents; one each had three, four, and five
accidents respectively. Twenty-eight accidents (72%) predominantly involved the
lower limbs, 12 (31%) involved the back/spine, 7 (18%) the upper limbs, and 1
(3%) was a head injury.
Discussion
To the authors’ knowledge this is the first
cross-sectional survey that examines the demographic, BASE jumping, and
morbidity characteristics in a population of BASE jumpers. The study has
captured a population of experienced BASE jumpers, who have been involved in the
sport for many years.
The findings suggest that the sport attracts predominantly
male participants in their mid-30s (participants become involved in the sport in
their mid-20s, when they gain sufficient skydiving experience and the required
maturity, and continue with the sport into their 30s), who are actively involved
in a number of other adventure sport activities.
The participants generally BASE jumped from all four
categories of fixed objects, without indentifying any specific object
preference. Sufficient data was not collected to determine whether accident
frequency was related to particular jumping sites or objects.
The accident rate of 0.4% is exactly the same as that of a
recent report by Soreide et al which examined injury rates from BASE
jumping from a single site (Kjerag Massif) in
Norway.7 However, in contrast to the findings
by Soreide et al (who found that most BASE jumping injuries were
minor), 75% of injuries recorded in our study were moderate or severe.
Possible explanations for this difference include: (a) the
Kjerag Massif is considered among the BASE jumping community to be a
“safe” object to jump from. This is because the cliff is high
(1000m) and therefore allows greater speed before parachute deployment and
control by jumpers, (b) it has a clear landing area, (c) it is a legal launch
site and therefore more dangerous, rushed, or night time jumps (to avoid
authorities) are unlikely to occur, and (d) the site is known to attract
beginner as well as experienced jumpers.
The inclusion of a high number of beginners may
paradoxically decrease the risk of injury severity as they do not generally
attempt “complex manoeuvres” that are more commonly associated with
severe injuries.
The overall risk of non-fatal injury associated with modern
skydiving has been estimated to be between 48 and 174 per 100,000
jumps.4,9 Risk of injury from BASE jumping in
this study is three to eight times higher (394 per 100,000 jumps). Moreover the
rate of injuries requiring hospitalisation in our study was 294 per 100,000
jumps and 16 times higher than that found by Burrows et al (18 per
100,000 jumps) in their study freefall skydiving
injuries.4
The BASE jumpers in this study appear to have a reasonable
understanding of the rate of injury associated with the sport, as they
“estimated” that the accident frequency from BASE jumping is 0.5%
which is very similar to the accident frequency found in the study (0.4%).
The majority of accidents (80%) involved significant
injuries to the lower limbs and spine, and the overall severity of these
suggests that BASE jumping injuries are likely to present a significant burden
to health services, particularly hospital accident and emergency, trauma, and
rehabilitation departments. They are also likely to contribute to persisting
chronic disabilities and significant loss of productivity.
Several methodological limitations need to be considered in
interpreting the results of this study. The population was not a random sample.
All participants who volunteered were included and the sample size was
relatively small. This may have lead to selection bias as those jumpers who had
experienced prior accidents may have been more motivated to share their
experience and therefore more likely to participate in the study.
As the study included only active jumpers, cautious BASE
jumpers, who had given up the sport following an injury or a
“near-miss” experience, may have been excluded. The sample may
therefore represent those with a particularly high risk-taking propensity.
Alternatively the sampling process may have excluded particularly high-risk
groups; as less experienced, more impulsive and higher risk-taking jumpers may
have been involved in fatal accidents at earlier stages of their BASE jumping
careers and therefore were unavailable for inclusion in the study.
Of concern, Soreide et al found the death rate associated
with BASE jumping from the “safe” Kjerag Massif to be
0.04%.7 Given the greater severity of injuries
found in our sample we are concerned that our population presents an even higher
risk of mortality, and intend to undertake 2- and 5-year follow-ups of this
population to determine whether this is the case.
Competing interests: In the past EM
has worked as a mountain and jungle guide (12 years ago) and mountain cycle
guide (6 years ago). OM-D is an active BASE jumper and has worked as a
promotional stuntman.
Author information: Erik Monasterio,
Consultant in Forensic Psychiatry and Senior Clinical Lecturer, Medlicott
Academic Unit, Hillmorton Hospital, Christchurch, New Zealand; Omer
Mei-Dan, Department of Orthopedic Surgery, Meir University Hospital, Kfar-Saba,
Israel
Acknowledgement: We are grateful to Dr Ceri
Evans for his helpful comments in the preparation of this article.
Correspondence: Dr Erik Monasterio,
Medlicott Academic Unit, Hillmorton Hospital, Private Bag 4733, Christchurch,
New Zealand. Fax: +64 (0)3 3391149; email: erik.monasterio@cdhb.govt.nz
References:
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