Risk of dying after a free fall from height

Pmnsic science Forensic

ELSEVIER

Science

7X (1996)

International 187Tl91

Risk of dying after a free fall from height Daniele RisseP*, Anneliese Bijnsch”, Barbara Schneiderb, Georg Bauer” “Institute bInstitute

of Forensic Medicine, Unicersit), of’ Vienna, Sensengasse qf‘ Medical Statistics and Documentation. Schn,clrlspanier,strq~e il - 1090 Vienna. Austria

Received

22 August

1995; revised

I5 November

2. A-1090 Vienna, 17. Unirersit~~

1995; accepted

1 I December

Aurtriu of Vientm.

1995

Abstract Falls from height are predominantly an urban phenomenon and represent an important form of blunt trauma. Disagreement predominates regarding the height at which death results. The aim of this study was to investigate the risk of dying after a free fall from height in relation to the distance fallen. Therefore, medical records of victims of a fall from height treated in 1989 at Viennese emergency units were analysed. In addition, post-mortem reports of deaths due to falls from height, examined in the same year at the Institute of Forensic Medicine in Vienna, were studied. For the purpose of an homogenous investigation sample in regard to physical condition, only people aged from 20 to 50 years were taken into account. A total of 11 females and 30 males suffered an accidental fall from buildings, seven men from scaffolding and two men from a tree. A total of 18 females and 18 males jumped from residential buildings. One woman and nine men intentionally fell from other buildings. All victims landed on concrete or pavement. Suicidal jumps occured from significantly higher places than accidental falls. The results of this analysis suggest that death usually occurs when distance is more than five storeys. Keywords:

Free fall; Height; Risk: Death

1. Introduction

Falls from height, defined as an unimpeded drop of a body from a known point to a known impaction point, are predominantly an urban phenomenon and represent an important form of blunt trauma in society [l-3]. High free falls are *Corresponding 0379-0738/96/$15.00 SSDI

author. 0 1996 Elsevier

0379-0738(95)01885-M

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either the result of an accidental event or a usual method of committing suicide. In addition, some cases of homicide are also described [4-91. ,Most studies on this topic investigated in detail the extent and pattern of injury correlating with height of fall, velocity of fall and point of impact [2-4,10,11]. Naturally, the severity of injury after a free fall and thus the outcome is primarily dependent on the distance fallen [3,11]. However, disagreement predominates regarding the height at which death results. It has been proposed that death usually results when distance is more than six storeys [12]. Nevertheless, there are reported survivals after much higher falls [l, 13- 151. The aim of this study was to investigate the risk of dying after a free fall from height in relation to the distance fallen.

2. Methods

For this purpose medical records of victims of a fall from height treated in 1989 at Viennese emergency units were analysed. The study also included post-mortem reports of deaths due to falls from height, examined in the same year at the Institute of Forensic Medicine in Vienna. Due to the fact that mortality after a fall is significantly influenced by the age of the victim [16], only persons aged from 20 to 50 years were taken into account. Thus, people of our investigation group resembled each other to a greater or lesser extent with regard to their physical condition. Based on the Manual of the International Statistical Classification of Diseases, Injuries, and Causes of Death (ICD) [17] the following falls were included in this study: 1) unintentional falls from a scaffolding, a building or another structure; 2) falls from one level to another level; 3) intentional falls from a dwelling-house or other buildings. Heights of falls were calculated from the available reports. In accordance with previous studies a storey was more or less arbitrarily calculated as 3.6 m [6,11,18]. The height of window-sills was assumed to be about 1.2 m. In case of a fall from scaffolds, etc. the height was calculated against the 3.6 m/storey standard. Data were reported as mean + standard deviation (SD.). We considered differences significant at P < 0.05. SAS 6.080 (SAS Institute Inc., Cary, NC, USA) was used for numerical analysis.

3. Results

Post-mortem reports of 32 cases examined at the Institute of Forensic Medicine in Vienna in 1989 were analysed for this study. In addition, the medical records of 64 patients, treated at an emergency unit, were investigated. A total of 11 females and 30 males suffered an accidental fall from a building, seven men from a

D. Risser

Table Study

I population

et al. i Forensic

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(n = 96) Survivors

n

Age (years) mean Height (m) mean Range

k SD. f SD.

Deaths

Female

Male

Female

Male

16 29.6 + 7.9 7.7 + 6.3 1.2 19.2

48 32.3 + 8.3 7.8 * 4.4 1.2 15.6

14 34.1 f 7.8 17.4 * 5.4 12 - 33.6

18 36.0 + 9.9 16.5 k 13.2 4.8 - 65.0

scaffolding and two men from a tree. A total of 18 females and 18 males jumped from residential buildings. One woman and nine men intentionally fell from other buildings. All victims landed on concrete or pavement. In our study population the ratio between females and males was almost 1:2 (Table 1). The height of fall ranged from 1.2 m (window-sill) to 65 m (Tower of the Cathedral of St. Stephen). Suicidal jumps occurred from significantly higher places than accidental falls (14.0 x 9.9 vs 7.9 x 5.2 meters; Wilcoxon two-sample test: P < 0.0001). There was no statistically significant association between the following factors: gender and age of the victim, gender or age and reason for fall, gender or age and distance fallen, gender or age and outcome. In our homogenous study sample, death usually resulted when the distance was more than five storeys (Table 2). There was almost no difference regarding the survival rate after a fall from the first floor and the second one. In relation to the outcome after a fall from the first floor, the risk of dying increased: 6.4 times after a fall from the third storey, Table 2 Risk of dying

after

a free fall from

height

(n = 96)

Storey

Meters

Survivors/deaths

Ground floor 1st floor 2nd floor 3rd floor 4th floor 5th floor > 5th floor

1.2 4.8 8.4 12.0 15.6 19.2 > 19.2

11/o 1612 1812 10:8 l/9 2/l o/4

11.1 10.0 44.4 56.2 77.8 100.0

64132

33.3

Total

a OR, odds ratio. b CI, confidence interval. ’ Referent.

‘% Deaths

OR”

95% CP

I .oo’ 0.89 6.40 10.29 28.00

0.11 --I.06 1.12-36.44 I .75-60.45 3.26-240.81

00.0

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10 times after a fall from the fourth storey and 28 times after a fall from the fifth storey.

4. Discussion The results of this analysis of free falls from height by people aged from 20 to 50 years suggest that death usually occurs when distance is more than five storeys (19.2 m). Nevertheless, Layton described the circumstances which allowed a young man attempting suicide to survive a 17-storey free fall [l]. Furthermore, military personnel survived falls from 1200 and 35 000 feet [13,14], and suicides survived jumps off the Golden Gate Bridge (73 meters) [15]. However, in all these cases the point of impact was not concrete, as in our sample [lo]. Naturally, the severity of injury and thus the mortality after a free fall is primarily dependent on the distance fallen [3,11]. The higher the fall the higher the velocity of the falling body. At impact, kinetic energy is quadrupled if velocity is doubled [4]. In this context it must also be taken into account that bodies in free fall from great heights seem to strike the ground exclusively head-first [18]. However, Weiler reported severe head injury as the main cause of death in his sample even after a free fall from less than 5 m. Thus, for example, two middleaged men died in our study population after a fall from the first floor because of sustained head injury [ 191. The age of the victim has also to be considered when discussing the outcome of a free fall. Trauma surgeons reported an association between the age of the victim and the extent of injuries [3,5,11]. Therefore, age has been included in the calculation of a number of trauma scoring systems [20,21]. In general, higher age is associated with a lower physical condition. The increasing fragility of bone in the elderly and the liability of elderly patients to succumb to fracture, contribute particularly to morbidity and mortality in the older age-groups after a fall [16]. For example, Berghaus, whose study population consisted of more than 40 percent of people older than 50 years, reported a lot of deaths even after a fall from less than 5 m [22]. In contrast, young people are more likely to survive even after a fall from greater heights. Regarding our sample, therefore, it is not surprising that those two women in our sample who did not die after a fall from the fifth floor in spite of severe injuries were about 24 years old. In summary, we have shown that in our homogenous study sample survival after a free fall with impaction on concrete is highly unlikely if the distance fallen is more than five storeys (19.2 m). Finally, although falls from height are less common than polytrauma due to automobile accidents [5,23], expert witnesses for traffic accidents frequently compare kinetic energy released by a frontal car collision with corresponding heights of falls to illustrate the risk of dying according to the velocity of collision [24]. In this context it must be taken into account that the distinct form of blunt multiple trauma due to free fall from height varies considerably from the horizontal deceleration of vehicular accidents [2,11].

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Acknowledgements The authors would and comments.

like to thank Miss Joanne Lenney for her helpful assistance

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