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The impact of alcohol intoxication in patients admitted due to assault at an Australian major trauma centre: a trauma registry study from 1999 to 2009
  1. Michael M Dinh1,
  2. Kendall J Bein2,
  3. Susan Roncal3,
  4. Alexandra L C Martiniuk4,
  5. Soufiane Boufous5
  1. 1Trauma Department, Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia
  2. 2Emergency Department, Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia
  3. 3Department of Trauma Services, Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia
  4. 4The Injury Division, The George Institute for Global Health, University of Sydney, Sydney, New South Wales, Australia
  5. 5Injury and Musculoskeletal Division, The George Institute for Global Health, Sydney, New South Wales, Australia
  1. Correspondence to Dr Michael Dinh, Trauma Department, Royal Prince Alfred Hospital, Level 10, Missenden Road, Camperdown, NSW 2050, Australia; dinh.mm{at}gmail.com

Abstract

Objective To examine the long term trend in assault admissions at an inner city major trauma centre and determine the association between clinical evidence of alcohol intoxication and major trauma due to assault.

Methods Adult trauma patients admitted due to assault between 1999 and 2009 were identified through the hospital based trauma registry at an inner city major trauma centre in Sydney. Demographic data, incident details, clinical evidence of alcohol intoxication, injury severity scores and injury related outcomes were collected. Population based incidences were calculated and outcomes compared between intoxicated and non-intoxicated patients. Major trauma was defined as a composite outcome of severe injury (injury severity score>15), intensive care admission or in-hospital mortality.

Results There were 2380 patients analysed. Clinical evidence of alcohol intoxication was documented in 12% (287/2380) of cases. There was a marked peak in incidence of hospital admissions due to assault which occurred between 2000 and 2002. Overall, the rate of hospital admissions due to assault decreased during the study period (incident rate ratios 0.94, 95% CI 0.90 to 0.99, p<0.001). The odds of major trauma were three times higher in patients with clinical evidence of intoxication compared to those that did not (adjusted OR 2.9, 95% CI 2.1 to 4.0, p<0.001).

Conclusions There was a peak in hospital admissions due to inner city assault around 2000–2002 associated with an overall decline in hospital admissions at this trauma centre over 10 years. Clinical evidence of alcohol intoxication in patients admitted for assault appears to be associated with more severe injury, including severe head injury.

  • violence
  • alcohol abuse
  • epidemiology
  • head
  • major trauma management
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Introduction

There is substantial evidence in the scientific literature supporting the association between alcohol intoxication and a range of related harms, including assaults.1–3 In a multinational study, the attributable risk of injury associated with alcohol use was highest in violence related injuries.2 Injuries and hospitalisations due to assaults are therefore one of the important markers of the health burden of alcohol use in society.

A recent population based study in the state of Victoria, Australia reported an increase in the incidence of severe injury due to assaults between 2001 and 2007.4 Fortunately most assaults do not result in major injury and this may skew the interpretation of injury trends.5 In addition there may be significant regional and local variations in patterns of assault injury due to social factors such as drug abuse and alcohol consumption.6 Sydney and the surrounding local government areas have a relatively high density of alcohol outlets and premises within the area.7 In particular, the City of Sydney has the highest absolute number of 24-h liquor licences in Australia.7

The present study was undertaken to: (1) describe long term incidence trends in hospital admissions due to assault within the direct catchment area of an inner city major trauma centre; and (2) examine the association between major trauma and clinical evidence of alcohol intoxication.

Methods

Setting

The Royal Prince Alfred Hospital (RPAH) is an inner city major trauma centre in Sydney, New South Wales. Sydney is Australia's most populous city with a population of around 5 million people.7 A single data abstractor (SR) has collected data prospectively into the trauma registry since 1991. There were around 2500 trauma and injury related in-patient admissions a year to this institution, with only around 1–2% being for gun related penetrating trauma. Patients were included in the trauma registry if the primary diagnosis or reason for admission was an injury. Data were submitted to the New South Wales Institute of Trauma and Injury Management annually for external auditing purposes.

Study design

This was a retrospective study of patients identified from the RPAH Trauma Registry from 1 January 1999 to 31 December 2009. Inclusion criteria were patients aged 15 years and over with in-patient hospital admission due to an assault incident occurring within the direct catchment areas of RPAH. The direct catchment area of the hospital was defined by the inner west local government areas and parts of the City of Sydney council area that fell within ambulance referral boundaries during the study period. Patients where incident postcodes occurred outside this catchment area were excluded. Both penetrating and blunt mechanisms of injury were included, however self inflicted injuries, sexual assault and domestic violence injuries were excluded. Transfers from other health facilities were also excluded. We extracted demographic data and incident details, including incident place and postcode. Emergency department triage times were used as a surrogate for incident time. Weekends were defined as occurring between the hours of 20:00 Friday through to 08:00 Monday. Study protocols, study dates, inclusion criteria and data extracted were all defined prior to data analyses.

Patient data

Mechanism of injury was categorised as blunt or penetrating (stabbing, shooting or other sharp objects), depending on the predominant or most severe injury recorded. Clinical evidence of alcohol intoxication on presentation was routinely abstracted from medical and ambulance records since 1998. Clinical evidence of alcohol intoxication was recorded in the trauma registry as present if terms such as ‘intoxicated, smells of ETOH, alcohol’ or similar were present or indicated in emergency triage notes or structured trauma admission forms. Evidence of intoxication was also retrospectively abstracted from medical records using International Classification for Diseases (ICD-10AM) coding and linked to trauma registry data using medical record number and date of presentation. Body region abbreviated injury severity scores (ISS) and overall ISS were used to describe injury profiles.8 Severe injury was defined as an ISS≥16.

Outcomes

Incidence rates for hospital admissions due to assault were expressed as assaults per 1000 reported assaults. The primary outcome was major trauma which was defined as a composite outcome of severe injury (ISS≥16), intensive care admission or death. Severe head injury (head ISS≥3) was also used as a secondary outcome. Rates of assaults reported to police within the direct catchment area of the hospital were obtained from the New South Wales Bureau of Crime Statistics and Research.

Statistical analysis

Continuous variables were expressed using medians with IQR and compared using the Wilcoxon rank sum test. Categorical data were compared using χ2 tests. Multivariable logistic regression was used to obtain adjusted OR for outcome variables, and negative binomial regression was used to test the hypothesis of a trend in rate of hospitalisation due to assault using reported assaults in the direct catchment area per year as the exposure variable. All variables compared in univariate analyses (age, mechanism of injury, time of injury and incident locations) were considered a priori in multivariate modelling. OR and incident rate ratios (IRR) were expressed with 95% CIs. Data were analysed using Stata V.10.1.

Ethics approval for this study was obtained by the Sydney South West Area Health Service Hospital Ethics Review Committee (RPAH zone).

Results

Patient population

There were 2391 patients who met the inclusion criteria out of a total of 31 727 patients in the trauma registry (7.5%). Of these, 11 patients (0.5%) had missing data on outcomes, leaving 2380 cases available for analyses.

Men comprised 85% of the population and the median age was 32 years (IQR 24–42). Ten per cent of the study population were aged between 15 and 20 years. The median ISS score was 4 (IQR 1–4) and 10% of admissions were classified as having major injury.

Clinical evidence of alcohol intoxication was documented in 12% (287/2380) of cases. Fifty-one per cent of patients presented between the hours of 20:00 Friday to 08:00 Monday (1173/2297) (figure 1). The breakdown of incident locations is shown in figure 2. Of note, 58% of incidents occurred on streets, railways or other public places and only 4% occurred in hotels or clubs. The overall mortality rate in the study population was 1.1% (26/2380), with a significantly higher mortality rate in the penetrating assault group compared to blunt assault (4%, 16/398 vs 0.5%, 10/1993; p<0.001).

Figure 1

Assault admission by day of week (n=2391).

Figure 2

Incident location type for patients admitted after assault (n=2931).

Figure 3 shows the 11-year trend in rates of hospitalisations per 1000 assaults reported to police in the direct catchment area between 1999 and 2009. Between 1999 and 2002 there was an 82% increase in the rate of hospital admissions due to assault. This was followed by a marked decline in the rate of hospitalisations due to assault associated with a slight decline in the rate of reported assaults. Overall the rate of hospital admissions due to assault decreased slightly during the same period (IRR 0.94, 95% CI 0.90 to 0.99, p<0.001).

Figure 3

Trend hospitalisations due to assaults (rate per 1000 assaults reported to police) at Royal Prince Alfred Hospital from 1999 to 2009.

Outcomes

There was no association between age group and major injury. However, major injury was significantly associated with men compared to women (11% vs 6%, p=0.008), penetrating versus blunt injury mechanism (22% vs 8%, p<0.001), incidents in hotels or clubs compared to other incident locations (21% vs 10%, p<0.001) and clinical evidence of alcohol intoxication compared with none (18% vs 8%, p<0.001).

When comparing study groups, patients with clinical evidence of alcohol intoxication had higher rates of major trauma and severe head injury (table 1). No significant difference was found in median length of stay.

Table 1

Comparison of assault patients with intoxication versus non-intoxication with respect to baseline characteristics and outcomes

Using a multivariate model adjusting for age, mechanism (blunt vs penetrating), gender, intoxication, incident place (other vs hotel or club) and incidents on weekends, the odds of major trauma were three times higher in intoxicated patients compared to non-intoxicated patients (OR 2.9, 95% CI 2.1 to 4.0, p<0.001) and around two times higher for incident location in hotels or clubs compared to other locations (OR 1.9, 95% CI 1.1 to 3.5, p=0.01). Using the same model, the adjusted odds of severe head injury (head ISS≥3) by itself was also three times higher in intoxicated patients compared to non-intoxicated patients (OR 2.7, 95% CI 1.9 to 3.9, p<0.001).

Discussion

The findings of the present study suggest that hospital admissions due to assault at this inner city trauma centre peaked around 2002 and fell dramatically afterwards. Clinical evidence of alcohol intoxication was significantly associated with higher odds of major trauma and severe head injury even after adjusting for age, sex and incident location.

The apparent peak in hospital admissions due to assault between 1999 and 2002 has not been reported elsewhere. Reports from the NSW Bureau of Crime Statistics around the same time suggested a significant increase in armed robberies and related assaults reported to police.9 In contrast a household survey conducted by the Australian Bureau of Statistics reported a stable rate of assault across New South Wales during this period.10 Reports from Victoria showed a 50% increase in alcohol related assaults and hospitalisations from 1999 to 2008.11 The reason for the marked decline in hospital admissions due to assault after 2002 is unclear, but has been postulated to be partly due to the decline in heroin trafficking activity and related armed assaults and robberies around the same time.9 In addition, a number of inner city areas in Sydney implemented Liquor Licensing Accords in 2003, with the aim of curtailing alcohol related crime and violence around local inner city premises.7–12

Although there is extensive literature available on the association between alcohol and assaults, there is little evidence to date that the presence of alcohol directly impacts trauma related outcomes after assault. A Finnish study showed that increasing blood alcohol levels correlated with increasing risk of head injury after assault.13 The present study adds to this by demonstrating that clinical evidence of alcohol intoxication, by itself, increases the odds of severe head injury and major injury in general.

Alcohol has a devastating impact on individuals and society. The financial impact of alcohol on Australia in terms of injury and rehabilitation, disease burden, lost productivity and other intangible losses is reported to be around $36 billion per year.14 Severe brain injury alone costs Australia $4.5 million dollars per incident case.15 The National Preventative Health Taskforce has identified alcohol (along with tobacco and obesity) as one of the major public health issues in need of action.16 Debate continues around the most cost effective measure to reduce the health and societal burden imposed by alcohol. The Royal Australasian College of Physicians recently released a position statement advocating the use of increased taxes on alcoholic beverages to reduce consumption, which is supported a number of published reviews.17–20

The limitations of this study include the reliance on data abstraction of alcohol intoxication from clinical notes. Information was routinely abstracted from ambulance sheets, triage descriptions and clinical notes. The authors acknowledge that reliance on clinical evidence of intoxication probably resulted in substantial under-reporting and misclassification of alcohol intoxication. From an empiric standpoint, clinical reporting of intoxication is more likely to occur when signs of intoxication are more apparent. Thus patients reported as clinically intoxicated in this study were more likely to represent the subset of patients who were more heavily intoxicated. Interestingly, a large multicentre trial of emergency patients published in 2005 found that 86% of patients with a blood alcohol concentration greater than 0.06 g/dl were correctly classified by emergency doctors as intoxicated, whereas only 1% of patients who were heavily intoxicated were incorrectly classified as non-intoxicated.21 Nevertheless the reliance on clinical documentation exposes flaws in current methods of assessing the burden of alcohol use at this and many other Australian trauma centres, and efforts are under way to obtain routine blood alcohol measurements as well as validated alcohol use screening tools on all injury related admissions to this institution. To the authors’ knowledge, no other trauma centre in New South Wales routinely undertakes this practice and it is not a current criterion for Australian College of Surgeons trauma centre verification.22 In contrast, screening for harmful alcohol use, including blood alcohol levels, became an essential criterion for trauma centre verification under the American College of Surgeons Committee on Trauma guidelines in 2006, based on evidence of the benefit of in-hospital brief intervention.23

The apparent fluctuations in assault admission rates at this hospital may reflect ambulance referral patterns to another smaller trauma centre (St Vincent's hospital) within the City of Sydney local government area. The NSW State Trauma plan, which changed ambulance referral configurations in this area, did not come into effect until 2010 so the effect of this is likely to be small. The study included only patients transported within the direct catchment area of the hospital which was not dependent on hospital bed availability or pre-hospital referral patterns. Nevertheless, problems with interpreting population based data exist when more than one trauma centre services a given geographical area, or when patients who do not reside within the same area are included. It would be informative to investigate whether trends in alcohol related trauma and assaults were replicated elsewhere in New South Wales.

In conclusion, clinical evidence of alcohol intoxication in patients admitted for assault appears to be associated with more severe injury, including severe head injury. However, more objective measures of alcohol related harm are required to more accurately assess the burden of alcohol in injury in Australian trauma centres.

Acknowledgments

We thank Professor Don Weatherburn from the New South Wales Bureau of Crime Statistics and Research for access to data relating to assaults within the RPAH area.

References

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Footnotes

  • Contributors MD: study design ethics and manuscript preparation. SR: data abstraction. KB: data coding and analysis. CB: study design and manuscript review. AM: data analysis and manuscript review. SB: data analysis and manuscript review.

  • Competing interests None.

  • Ethics approval Sydney Local Health District Research Ethics Committee (RPAH zone).

  • Provenance and peer review Not commissioned; externally peer reviewed.

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