The western australian road injury database (1987-1996): ten years of linked police, hospital and death records of road crashes and injuries.

Accurate information about injuries and their causes is essential to road safety research, policy development and evaluation. Such information is most powerful when it is available for all road crashes within a jurisdiction. The Western Australian Road Injury Database achieves this through the on-going linkage of crash details from reports to police with the details of injuries to casualties contained in hospital and death records. Over the 10-year period 1987-1996, 386,132 road crashes involving 142,308 casualties were reported to the police in Western Australia. There were also 47,757 hospital discharge records and 2,906 death records related to road crashes during this period. Of the 142,308 police casualties, 17 848 had a matching hospital discharge record and 2,454 had a matching death registration. Linkage within the hospital records revealed that the 47,757 discharge records involved 43,179 individuals, of whom 39,073 were admitted to hospital once, 3,653 were admitted twice, 374 were admitted three times and 78 were admitted more than three times. Of the 43,179 hospitalised casualties, 817 had a matching death record. Linked police, hospital and death records of road crash casualties provide accurate outcome information for casualties in crashes reported to the police. In addition, estimates of under reporting of crashes for different road user groups can be made by comparing hospital records with and without a matching police record. This article demonstrates the power of a linked system to answer complex research questions related to outcome and under-reporting.

A linkage study of Western Australian drink driving arrests and road crash records.

Records of drivers in all reported road crashes occurring in Western Australia between 1987 and 1995 were linked with records of all drink driving arrests in the same period. About 7% of all drink driving arrests occurred because of a road crash. Differences were observed between these drink-driving crashes and other types of road crashes. Drink driving crashes tended to be more severe than those not involving alcohol. Serious crashes (involving fatalities or hospitalisations) accounted for 20% of alcohol-related crashes, but only 6% of all crashes reported over the study period. From another perspective, crash-related drink-driving arrests were more likely than routine enforcement arrests to involve younger (18-35 years) and older (65 years and over) drink drivers. Routine enforcement arrests, on the other hand, were likely to involve a greater proportion of Aboriginal drivers.

Novice drink drivers, recidivism and crash involvement.

A group of drink drivers with no prior arrest for drink driving was selected from drink driving arrest records originating in Western Australia between 1987 and 1995. These drink-driving records were linked to road crash records for the same period. The analysis of these combined records focussed on the sequence of driving events (i.e., arrests, crashes and arrests resulting from crashes) and the present article explores the relationship in time between known drink driving incidents and crash involvement. Using multi-variate survival analysis, it was found that if a driver's first drink driving offence resulted from a road crash, especially if this occurred at a younger age, he/she was significantly more likely to drink, drive and crash again.

Complementing police road-crash records with trauma registry data--an initial evaluation.

This paper examines the consistency of hospital and police reporting of outcomes of road traffic crashes using a database of linked police crash reports and trauma registry records. Criteria for inclusion into the trauma registry include trauma-related causes with subsequent stay of more than 24 h or death due to injuries. During the 1997 calendar year there were 497 cases of road-related injuries within the combined trauma registry of Sir Charles Gairdner and Fremantle Hospitals, of which only 82% had matching police records. Linkage rates were associated with gender, injury severity and the number of vehicles involved. Within the road user category, pedestrians were least likely to link. Of the linked records, police classification of injury severity was correct in 78% of cases. Male casualties were more likely to be correctly classified than females, after adjustment for related variables including injury severity. Correct classification of injury by police was also closely related to severity of injury. Identification and targeting of these groups of casualties is vital in refining the road-crash reporting system. Increased crash reporting and availability of data from these two sources will provide road authorities with more reliable measures of injury outcome.

Comparison of accident and emergency with police road injury data.

This paper examines the consistency of police and hospital reporting of outcomes of road traffic crashes using a database of linked police crash reports and accident and emergency department data. The database used consisted of linked records of road traffic crashes in Western Australia for the period of October 1, 1987 to December 31, 1988 from police reported casualty crashes, the discharge records from all hospital admissions in Western Australia, the Registrar-General's death records, and records for each ambulance trip as a result of a road crash in the metropolitan area of Perth. The results suggest that police records of hospital admissions from the group of accident and emergency attendances underestimated the total by approximately 15%.

An evaluation of road crash injury severity measures.

Reliable and consistent measures of injury severity are necessary for the study of environmental, crash and personal factors involved in road traffic crashes. This study was designed to evaluate measures of injury severity derived from computerized hospital discharge records, using 3609 road crash casualties admitted to hospital in Western Australia in 1988. External cause of injury codes were used to identify injuries from road traffic crashes. The ICDMAP software was used to convert the diagnosis codes into Abbreviated Injury Scale (AIS) scores for each body region. The maximum AIS values were derived using (1) all 12 diagnosis codes; (2) the first six diagnosis codes; and (3) the principal diagnosis code alone. Other measures of injury severity evaluated were the number of body regions with at least one injury; the number of regions with Abbreviated Injury Severity score of three or more; and total number of days spent in hospital. Discriminant analysis suggested that the AIS could be separated into minor and major injuries at a score of three and the Injury Severity Score at a score of nine. The measures derived from the AIS were all strongly correlated with each other and with the length of hospital stay and the dichotomized values gave similar results to the other scores when used in regression analyses of the injury experience of different types of road users. It was concluded that measures incorporating elements of both severity and number of injuries were preferable but length of hospital stay would be a suitable proxy if no other injury information was available.

The feasibility of linking hospital and police road crash casualty records without names.

Government and other agencies routinely collect complementary information on road crash casualties and there may be opportunities to widen the scope of data available for research and policy evaluation if mechanisms can be established to combine these data sources. Where unit record data are available, direct links within and between individual records can often be achieved using record linkage techniques. Without the benefit of unique identifiers, sufficient other identifying information such as the full name, date of birth and sex of the casualty, their role in the crash and the date of the crash are required to enable correct links between individual records to be made. However, all these data items may not be available and it is therefore important to investigate the effect this may have on the quality and quantity of links between records. The research reported here used the hospital admission and police records from the Western Australian Road Injury Database, which had previously been linked using all the identifying characteristics mentioned above, special purpose software and comprehensive manual checking. This set of linked records were considered to be a "gold standard" which could be used to measure the quantity and quality of links produced using fewer identifying characteristics. Results from this process showed that about 90% of the original links could be identified when a phonetic code of the family name of the casualty was used with age, sex, road user type and crash date. However, only about 50% of the original links were found if linking was performed without using names or phonetic name codes.

Hospital inpatient costs resulting from road crashes in Western Australia.

The purpose of this study was to estimate the inpatient costs of road crashes in Western Australia, and to investigate factors relating to casualties and their injuries that affect the hospital costs resulting from road crashes. All road crash casualties who were injured severely enough to be hospitalised in Western Australia in 1988 were included. A casemix classification system was used to classify patients into diagnostic related groups. Hospital costs were assigned to individual patients on the basis of their diagnostic related group and length of hospital stay. The annual cost of hospital treatment for road crash casualties was estimated as $13.9 million, and 33 per cent of this was incurred by those with lower extremity injuries and 27 per cent by those with head injuries. Hospital costs per casualty ranged from an average of $1388 for those sustaining minor (Abbreviated Injury Scale severity score of 1 or 2) spinal injuries to $16,580 and $33,424, respectively, for those sustaining severe (Abbreviated Injury Scale severity score of 4 or 5) head and spinal injuries. A multivariate analysis of variance revealed the following factors as having a significant independent effect on the hospital inpatient costs of road crash casualties: type of hospital (teaching or nonteaching), body region of injury, injury severity level and road user group. There were also significant interaction effects between different factors. Since hospital inpatient costs vary considerably across factors, using average cost data in the specific economic evaluation of road safety interventions for groups of road users is inappropriate.

A comparison of hospital and police road injury data.

In order to gather as much information as possible on road crashes and outcomes, routinely collected police reports of traffic accidents and hospital discharge files were individually matched or "linked" using a computerised iterative procedure on name-identified data from both sources. The two groups of linked and unlinked hospital records were compared. Within the linked dataset, a comparison of like variables was made and showed good agreement between the two sources on accident type and road user type. However, police-reported levels of injury severity were shown to be less reliable. In addition, the proportion of hospital inpatient records that linked to a police record was found to be influenced by several factors. The overall linkage rate from hospital to police was 64% but varied from 29% for motorcyclists in single-vehicle accidents to 79% for motor vehicle drivers. The linkage rate increased with increasing levels of injury severity and was substantially lower for casualties of certain ethnic groups. It was deduced that for most instances where a hospital record did not link to a police record, the crash had not been reported. These findings confirm that there was considerable underreporting of hospitalised road casualties to the police and that the extent of underreporting was greater for those less severely injured.

The construction of a road injury database.

In order to effectively examine possible causes and determinants of road trauma, reliable information on the participants, circumstances, and resultant injuries and deaths must be available. Characteristics of participants (persons and vehicles) and the circumstances of road accidents are routinely collected by police and road authorities, whereas details of the injuries and medical care provided to casualties are collected by hospital and ambulance services. A road injury database, linking data collected by the Health, Police, and Main Roads Departments of the Government of Western Australia with records of the St. John Ambulance Association and the Death Register, has been established. This paper describes the procedures used to link the various sources of data and discusses the design, construction, and quality of the resultant relational database.

Travel exposure and choice of comparison crashes for examining motorcycle conspicuity by analysis of crash data.

Much research has been conducted examining the problem of motorcycle road crashes. Most of this research has concluded that motorcyclists have a conspicuity problem, particularly during the day. This type of research has often involved comparing multi-vehicle motorcycle crashes with single vehicle motorcycle crashes occurring during the day and night. The aim of this paper is to point out that comparison of single and multiple vehicle motorcycle crashes juxtaposes subsets of crashes with clearly different causes (car drivers' possible failure to detect a motorcyclist against motorcyclists' loss of vehicle control). Comparing groups of crashes for which conspicuity can be posited as a common cause (car drivers' possible failure to detect a motorcyclist or car) may be a more enlightening comparison. The issue of exposure is also examined in this paper.

Atrial fibrillation and mortality in an elderly population.

Prospective data from Busselton, Western Australia, collected during triennial surveys from 1966-81 with follow-up of subjects to 1983, showed that atrial fibrillation (AF) was frequent in elderly people and associated with increased mortality. Of 1770 people aged over 60 years, 40 were in atrial fibrillation when first seen and a further 47 developed it during follow-up. Atrial fibrillation was positively associated with angina, history of a myocardial infarction and left bundle branch block. Relative mortality in those with atrial fibrillation compared with those without it, was 1.92 for all causes, 1.82 for death from cardiovascular causes (excluding stroke) and 3.78 for deaths from stroke, after adjustment by proportional hazards regression for confounding effects of age, sex, history of a myocardial infarction, an abnormal electrocardiogram, angina, cholesterol level systolic blood pressure and Quetelet's Index (weight/height2). The excess relative mortality declined with increasing age for both women and men. This raised relative mortality remained constant with time from the first detection of AF for all causes and cardiovascular causes but appeared to increase with time from detection for stroke death. The risk of death from stroke was greatest in the younger women. The observed risk of death from stroke in patients with AF suggests that anticoagulant use should be considered in selected patients.