ACCid Ano/ & PRY, Vol. 13. pp. 3742. 19111 Pnnlcd m Great Britain. All rights reserved

ccn1475/81/01M374wn)6102/0 Copyright @ 15% Pergamon Press Ud

ROAD TRAFFIC ACCIDENTS AND THE ABBREVIATED INJURY SCALE (AIS) IN JAPANt

MASAHIKO TSUCHIHASHI and SHINHACHI NISHIKAWA

Department of Public Health, School of Medicine, Nihon University, Tokyo, Japan

Kerr MII Department of Nemo-Surgery, School of Medicine, Tokyo University, Tokyo, Japan

and

MASAAKI ORAMURA

Department of Emergency Medicine, National Fire Defense College, Tokyo. Japan

Abstract-Although in Japan the number of casualties from road traffic accidents decreased substantially during a period of improvement of safety measures, in recent years it has remained rather constant. To decrease accidents still further it is necessary to investigate the circumstances of road traffic accidents and the severity of resulting casualties in detail. For this purpose 167,721 cases of road traffic accident casualties occurring between February and April 1979, throughout Japan were analyzed. (I) It was found that 74.2% of all the cases suffered injuries corresponding to AIS-I; 39% of these involved neck injuries. (2) There were 2,654 fatal cases, 67% of which involved head injuries, chiefly cerebral contusion, cranial base fracture, and intracranial hemorrhage. There were fatal cases in the categories of AK-3 or below which are generally considered not fatal, but those were due to complications. (3) The chief sites of injury varied according to the victim’s mode of transport: in an automobile the neck was the site most frequently injured; on a motorcycle the legs and head were usually involved; on a bicycle or walking the head and legs were most at risk. (4) Injuries to pedestrians often fell under the severer AIM or higher codes and constituted 43% of total deaths. (5) Accidents with automobiles changing lanes tended to cause serious injuries and many deaths. Other characteristics of road tralIic accidents in Japan are analyzed and discussed.

INTRODUCTION

The number of casualties from road traffic accidents increased steadily in Japan after the end of World War II and became a serious social problem. The government made efforts to promote safety measures and reduce the number of road accidents, and, as a result, the number of casualties decreased after 1970, which was the turning point with a maximum of casualties. Recently, however, this tendency is slacking off, and the number of accidents threatens to rise again. We now have an urgent need for more powerful and radical preventive measures. In addition an efficient emergency care system for road traffic accident victims-rescuing activities and emergency departments in hospitals-is also urgently needed, though recently many improvements have been made.

For this purpose not only the conventional road traffic accident statistics but detailed epidemiological studies are required to serve as the basis for effective measures. The present investigation tries to establish a standardized method for road traffic accident survey and provide basic data for the evaluation and improvement of road traffic safety measures and the emergency care system.

MATERIAL AND METHOD

The material of the present study consists of 167,721 traffic-accident casualties reported to the Automobile Insurance Rating Association of Japan during the three-month period beginning February, 1979.

Motor vehicle insurance in Japan is composed of compulsory automobile liability insurance (CALI) and voluntary insurance. CAL1 is specified in the Motor Vehicle Liability Security Act (1955), under which every motor-vehicle owner (with certain rare exceptions) is required to have a contract with a recognized insurance company. Twenty domestic and twelve foreign companies operate in Japan.

Compensation claims are handled not by the individual insurance companies but by the Automobile Insurance Rating Association of Japan, which was jointly established by the 32 insurance companies and operates through 82 branches throughout Japan using compensation

tsponsored by the Emergency Medicine Research Committee, Japanese Council of Traffic Sciences.

37 MP Vol 13. No. I- < *

38 M. TSUCHIHASHI ef al

rating criteria designated by the government. Thus the information of all traffic accident compensation claims is forwarded to one place for rating.

The information obtained includes: (1) An accident certificate issued by the police: (2) A medical certificate or death certificate: (3) A summary of the medical care rendered provided by the hospital: (4) Miscellaneous additional papers necessary for rating.

From these items were obtained such data as: (1) The age, sex, occupation, and place of residence of the victim, and the type of automobile involved; (2) The victim’s mode of transport at the time of the accident; (3) The date, time, weather, place, situation, road type, and other information relevant to the accident; (4) The medical findings; (5) The medical institution to which the victim was referred; (6) The treatment and result; (7) The period of treatment or time before death.

The reported injuries were classified according to the Abbreviated Injury Scale [American Association for Automotive Medicine, 19761. Severity scaling required about 6 months for 20 clerks who had been specially trained for the task. This group could process about 1,200 cases per day. The data were entered into a computer (IBM 3031) for later analysis of the relationship between the kind of accident, the victim’s mode of transport, the body region affected and the severity of the injury sustained.

RESULTS

Of the 167,721 casualties studied, males constituted 66.5% and females 33.5%. This ratio was nearly the same as the national figures given in the Statistics of Road Traffic Accidents in Japan, 1978, compiled by the National Police Agency, i.e., 69.2% and 30.8% (Table 1).

Table 2 shows the severity of injuries suffered classified according to AIS. When multiple injuries were present, the most serious one, or the one most likely to affect the prognosis was taken up for study. A majority of 72.2% of the casualties came under the category of AH-l, indicating that most of road traffic accident casualties were of a mild degree. Those belonging to category AIS- or over, which effectively means the injury might be fatal, were 5,084 or 3.1% of all casualties. The 130deaths among those of AIS- to 3, i.e. those with minor injuries, were brought about by complications such as infection, fat embolism, cerebral apoplexy, etc.

Table 3 shows the total number of casualties as classified by the body region affected. The total number of casualties was 271,175, i.e. 1.6 injuries per person. The body region most frequently affected was the neck: 99.1% of these injuries were coded AIS- or 2. Neck injuries of AIS- or above were very few. Those with minor neck injuries alone constituted 36.7% of the total casualties; the majority of such injuries were the socalled “whiplash injury of the neck”.

The body region most frequently affected with injuries of AIS- and over was the head. Abdominal injuries, though few in number, tended to be serious, as the proportion ((B/A) X 100) of serious ones, 24.3%, was the highest.

Table 4 shows the regions of fractures. The total number of fractures was 38,597. Fractures of the tibia and fibula constituted 21.3% of all fractures, while fractures of the skull and the rib

Table I. Number of casualties

</

Table 2. AIS classification of casualties and fatal cases

I--- --.- Deaths B

(7-J i (001

Road walk accidents in Japan

Table 3. Total number of injuries by body regions

Body Regans Total No A % Total ho of AIS3-6 B 1

Herd + Face 59.R17 22 I 6.198 37.7

( Neck 78.983 29 I 750 46

/ Chest 14.409 53 2.485 15 I j Abdomen 6.581 24 I.596 9.7

Back + Pclns 15.629 58 373 23

~ LIpper Exlrcmmcr 27,753 102 I.173 7.1

Lower Extrem!ues 50.072 18.5 3.745 22.8

; Entut Body 17.931 66 119 0.7 I 1 Total 271.175 100.0 16.439 100.0

39

Table 4. Total number of fractures by body regions

Fracture Repruns Total No Z Fracture Regons Total No I /

H i Skull and Fac,al Bancr 4.980 12.9 f Humer”r I.018 2.6

+ E Rad,us and Ulna I.986 5.1

Clnv,clc and Scapula 3.818 9.9 5 Grpal Boner I ,440 37

~kb

i strrnum Ccrwcal Vcrtcbra

: Thoract< Vertebra

: Lumbar Vertebra

Pelwr Sacrum and Coccyx I58 458 I .2 Sub Total 1 12.969 14.858 38 5

Total 38.597 100.0

constituted 12.9% and 12.0% respectively. Of the skull fractures, 24.4% were fractures of facial bones.

Table 5 shows the number of casualties analyzed by the kind of accident. It was found that the largest number of casualties (43.8%) occurred in accidents between automobiles not involving a lane change, and 6 1.4% of those were rear-end collisions. The second most frequent were pedestrian-automobile accidents (17.3%), followed by motorbike-automobile accidents (15.2%). Casualties with AIS- and over were also analyzed according to the type of accident situation; the largest number of casualties was found with pedestrian-automobile accidents (30.1%), followed by motorbike-automobile accidents (23.2%). The highest proportion of serious injuries (AIS- and over) was found with accidents between automobiles and structures on the road and those between pedestrians and automobiles. In accidents between automobiles not involving a lane change the proportion of serious injuries was the lowest, though the number of casualties was very large.

Table 6 shows the total number of injured body regions classified by the type of accident situation. The most frequent category was neck injuries sustained in accidents between automobiles that were not changing lanes, but most of these were, as already mentioned, minor injuries of AIS-1. The next most frequent category was head injuries sustained in pedestrian- automobile accidents.

Table 7 shows an analysis of the casualties by the victim’s means of transport at the time of the accident. Casualties occurred most frequently while driving or riding in automobiles (55.4%) but serious injuries of AIS- and over occurred most frequently while walking. The proportion

Table 5. Casualties classified by type of accident situation

,

Typer of Situations Gsualues. A % casualocr of

AIS 3-6: B % $x 103%

AutomobdcAutomobde (chln@ng lanes)

(Not Chnn8mg Lanes)

Road Structure-Automobdc

la,s of Maneuverabdtty

Mo!orbike.Automobdc

&cycle-Automobile

Pedestrian-Automobile

No, SDccnied

10,653 6.4 I.204 8.5

73.424 43.8 2,253 IS.9

3.219 1.9 479 3.4

2.520 1.5 360 25

25,558 15.2 3,281 23.2

22,597 13.5 2.261 16.0

29.137 17.3 4.262 30.1

613 04 60 0.4

II.3

31

14.9

14.3

12.8

10.0

146

98

, Totll 167.721 100.0 / 14.160 100.0 84 1 I

Table 7. Casualties classified by victim’s means of transport at time of accident

J

of serious injuries scored AIS- and higher was greatest among those riding on the pillion seat of a motorbike (16.3%), and then among pedestrians (15.3%). Though the casualties among automobile drivers were very numerous, the proportion of serious injuries was low.

Table 8 shows the total number of injured body regions classified by the victim’s mode of transport at the time of the accident. Neck injuries sustained while driving or riding in automobiles were very frequent but usually of a minor nature within the range of AIS-1. The next most frequent were head injuries sustained while walking or riding in an automobile as a passenger.

Table 9 shows the casualties involved in large truck accidents categorized by the type of accident situation. In all situations accidents involving lane changes had a higher proportion of serious injuries than did other types of accidents. The highest proportion of serious injuries was 17.9% found in accidents between large and small trucks changing lanes. Among accidents not involving lane changes those between large trucks had the highest proportion of serious injuries.

Table 10 shows the number of casualties and fatalities distributed by the time of accident and the type of accident situation. Casualties most frequently occurred between 12:OO and 16:00 in all types of accident situations except for accidents between automobiles and dangerous roadwork structures which occurred most frequently between 0:OO and 4:O0. This might be attributed to reduced visibility at night and drowsy driving. The fatality rate was highest between 0:OO and 4:00 in all types of accident situations. In pedestrian-automobile accidents and automobile-automobile lane changing accidents, the fatality rate was about 1 in every 10 casualties.

DISCUSSION

In order to enforce effective measures for road traffic safety it is essential to grasp in detail the epidemiological characteristics of the casualties resulting from traffic accidents. The present

Table 8. Total number of injured regions classified by victim’s means of transport

Road traffic accidents in iapan

Table 9. Casualtics in large truck accidents ciassitied by type of accident situation

Is09 91 6.0

2.816 132 4.1

8259 334 4.0

!&212 I.269 23

Table 10. Number of casualtics and fatalities cisJs&d by type of accident Siren and time of accident occurrence

Types of Sltwtionr li Ttme of Acadent Occurrcnsr ; o-l 4-a 8-12 12-16 16-20 20-24 Tot11

Automobile - Automobile A 793 1.941 2.213 2,726 2,058 922 10.653

(Clungiing Lanes) B 15 66 S6 56 41 26 320

C 9s 3.4 2.5 2.1 2.0 2.8 3.0

Automobile - Automobile A 4,362 11,812 17,124 18,409 IS.684 6,033 73,424

@Jot Cbutgitl~ lanes) B : 55 52 37 47 40 29 260

C . 1.3 0.4 0.2 0.3 0.3 0.5 0.4

A 714 376 430 575 454 610 3.219

Road Structure - Automobile B ’ 29 12 I2 13 d 9 -I5 90

c 3.7 3.2 2.8 2.3 2.0 2s 2.8

Loss OS ~neuver~bdi~y

Motorbike - Automablie

Bicycle - Automobib

f / 7; ;i 7; u$ y,; E “1 I

1 A / 346 5.523 5,814 6,437 6,451 987 IS.558

/B’

jc j I6 70 68 90 82 31 357

4.6 I.3 I2 I .4 I .3 3.1 I4

IA 1 266 4,159 4,949 6,606 S.869 748 22.597

la

/ c ! 4’.: 2”: 94 88 107 21 ! 412

1.9 1.3 18 2.8 j I .8

Pedestrian - Automobde

Not Spwtied

TOllI

/A ; 812 3,371 6,061 9,368 7,812 1.713 29,137 ; lB’

c / 79 141 191 223 345 149 I.128 j

/ 9.1 4.2 32 24 4.4 0 7 3.9 / IA / 175 IS2 121 48 613 1

B i “i ‘: 6 3 2 I 14

C 00 2.6 3.5 2.0 1.7 21 2.3

A 7,724 27,621 37,?48 44,883 38,860 il.385 167,721

B 277 444 477 536 638 282 2554

c 3.6 1.6 1.3 I.2 I.6 25 I.6 j

A No. of Carurlt,er B- No ofDeaths C: +x I00

survey was made using data collected by the Automobile Insurance Rating Association of Japan which handles all insurance compensation claims throughout the country. The nature of the data source does not preclude a potential selection bias. There were a number of accident groups excluded form the present investigation:

(1) Those who had a CAL1 contract but made no claims for compensation. (2) Those driving special motor vehicles which were not under a CALI contract such as the

vehicles used by the government or foreign diplomats, or the ones used other than on public roads.

(3) Those where the responsible vehicles were not ident~ed ~it~nd-ins, etc.). It seems improbable that the omission of these groups has any significant influence on the results of the present survey.

The findings obtained in the present investigation are summarized as follows: (1) Of the 167,721 casualties, males constituted 66.5% and females 33.5%. The total annual

number of casualties from traffic accidents in 1979 was, according to the National Police Agency, 604,748.

(2) The fatal cases were 2,654, constituting 1.6% of the casualties studied. In this regard it was reported by the National Police Agency that the total deaths from traffic accidents were 8,461 in 1979.

42 M. TSUCHIHASHI et al,

(3) In spite of having suffered only minor injuries (AIS- or below, i.e. those not threaten- ing life) 130 cases died. Most of such deaths were caused by complications such as infection, fat embolism, etc. A more detailed study of these cases is to follow.

(4) Fractures occurred most frequently in the lower extremities, particularly in the tibia and fibula, followed by fractures in the skull and facial bones.

(5) Of the casualties, 72.2% involved only minor injuries of AIS-I. (6) The body region most frequently injured was the neck, but 99.1% of neck injuries were

scored only AIS-12. (7) It was the head that most often was involved among all injuries scored AIS- and over. (8) The abdomen was the region with the highest rate of serious injuries scored AIS- and

over. (9) It was pedestrians that suffered injuries of AIS- and over most frequently. (10) Among motorbike pillion passengers the rate of serious injuries scored AIS- and over

was high compared with the total number of casualties. (I 1) In accidents between large trucks involving a lane change a large proportion of injuries

were AIS- and over. (12) Casualties from collisions between automobiles and structures on the road often

occurred late at night. (13) The fatality rate was higher in accidents occurring late at night. One out of every ten

casualties died in pedestrian-automobile accidents and automobile-automobile accidents (in- volving a change of lanes) which took place between midnight and 4:00 AM.

REFERENCE

American Association for Automotive Medicine. Committee on Injury Scaling, The Abbreviated Injury Scale 1976 Revision. Morton Grove, IL 60053, U.S.A., 1976.