Elsevier

Injury

Volume 31, Issue 7, 1 September 2000, Pages 493-501
Injury

A comparison of patient characteristics and survival in two trauma centres located in different countries

https://doi.org/10.1016/S0020-1383(00)00029-2Get rights and content

Abstract

Introduction: The aim of the study was to compare patient characteristics and mortality in severely injured patients in two trauma centres located in different countries, allowing for differences in case-mix. It represents a direct bench-marking exercise between the trauma centres at the North Staffordshire Hospital (NSH), Stoke-on-Trent, UK and the Oregon Health Sciences University (OHSU) Hospital, Portland, Oregon, USA.

Methods: Patients of all ages admitted to the two hospitals during 1995 and 1996 with an Injury Severity Score >15 were included, except for those who died in the emergency departments. Twenty-three factors were studied, including the Injury Severity Score, Glasgow Coma Score, mechanism of injury and anatomical site of injury. Outcome analysis was based on mortality at discharge.

Results: The pattern of trauma differed significantly between Stoke and Portland. Patients from Stoke tended to be older, presented with a lower conscious level and a lower systolic blood pressure and were intubated less frequently before arriving at hospital. Mortality depended on similar factors in both centres, especially age, highest AIS score, systolic blood pressure and Glasgow Coma Score.

The crude analysis of mortality showed a highly significant odds-ratio of 1.64 in Stoke compared with Portland. Single-factor adjustments were made for the above four factors, which had a similar influence on mortality in both centres. Adjusting for the first three factors individually did not alter the odds-ratio, which stayed in the range 1.53–1.59 and remained highly significant. Adjusting for the Glasgow Coma Score reduced the odds-ratio to 0.82 and rendered it non-significant. In a multi-factor logistic regression model incorporating all of the factors shown to influence mortality in either centre, the odds-ratio was 1.7 but was not significant.

Conclusion: The analysis illustrates the limitations and pitfalls of making crude outcome comparisons between centres. Highly significant differences in crude mortality were rendered non-significant by case-mix adjustments, supporting the null hypothesis that the two centres were equally effective in terms of this short-term indicator of outcome. To achieve a meaningful comparison between centres, adjustments must be made for the factors which affect mortality.

Introduction

The designation of selected hospitals as trauma centres is an important part of trauma system planning. Expertise is maintained more easily by providing a high volume of experience and concentrating resources allows full tertiary trauma care to be rapidly available at all times. Evidence indicates that urban trauma systems have been effective in the United States [1], [2], [3], [4] but corresponding evidence is lacking in the United Kingdom [5]. In a comment on regional trauma system development in the UK, Yates pointed out that the cause, frequency and demographics of trauma vary significantly between the two countries [6].

Previous comparisons between trauma centres have tended to rely on methods such as TRISS, using norms derived from pooled data [7]. Such studies have been limited by the difficulty of validating data from a large number of hospitals as well as by the averaging process itself. An alternative approach is a direct comparison with an equivalent centre. Although few such studies have been reported [8], this benchmarking approach is becoming popular as a quality improvement strategy.

This study compares two urban trauma centres, one in the United States and one in the UK. Both centres have made substantial investments in trauma registries. Their databases contain details abstracted from the medical records by trained personnel. This information allowed a direct comparison to be made between the two centres, using methods which adjust for the observed differences in case-mix.

The North Staffordshire Hospital (NSH) served as a pilot trauma centre in the United Kingdom between 1990 and 1994 [9], [10]. It is a large acute hospital (1300 beds) in an area with a local population of 500,000 people. It is surrounded by five district general hospitals, resulting in a total catchment population of about 1.7 million. Since 1990, the NSH has served as a tertiary referral centre for severely injured patients in the North West Midlands. Although some patients with severe trauma were taken directly to the centre rather than to the nearest hospital, there was no legal requirement for such triage. Most patients were taken to the nearest hospital and, if necessary, transferred later to the centre.

The North Staffordshire Hospital Trauma Research Department collects data on all injured patients who stay longer than 72 h in hospital, are admitted to the ICU or are transferred from other hospitals, together with all deaths. These criteria with minor qualifications are required by the national Trauma Audit and Research Network (TARN), previously known as the Major Trauma Outcome Study (MTOS-UK) Group [11], [12], to which the NSH submits data.

The state of Oregon passed legislation in 1985, which assigned authority over designation of trauma centres to the State Health Division. In 1988, two Level I trauma centres were designated in Portland, one of which was Oregon Health Sciences University (OHSU). The Portland area is the state’s largest metropolitan region with a population of approximately 1 million. All seriously injured patients in this region who met triage criteria were transported from the scene directly to one of the two Level I trauma centres. These centres also received patients transferred from other hospitals throughout the state of Oregon, which has a population of approximately 3 million [13].

The OHSU Trauma Registry collects data on all patients entered into the trauma system by pre-hospital personnel and brought directly to the OHSU emergency department, as well as other patients transferred to the OHSU trauma service from other hospitals. The OHSU trauma registry also includes injured patients who present to and are admitted from the OHSU emergency department following injury without being entered into the trauma system by pre-hospital personnel.

Section snippets

Factors and outcomes studied

The cohort selected for study were patients admitted to the two trauma centres who had an Injury Severity Score (ISS) [14] over 15. Included in the analysis were patients who presented to the trauma centres from the scene of injury and those who were transferred there after first being treated at another hospital. The patients were all treated in the years 1995 and 1996. Those patients who were dead on arrival at the emergency department or died in the emergency department were excluded from

Patient characteristics: Stoke vs Portland

Table 2, Table 3 and Fig. 1 show single factor comparisons between the two centres. Table 2 contains simple demographic information, while Table 3 focuses on information relating to the processes of care, such as length of stay in the ICU or in hospital. Fig. 1 illustrates the differences in the body regions injured.

Of the 23 factors studied, only seven showed no significant difference between Stoke and Portland. These were year, quarter, day of admission, sex, medical history, ISS and the

Discussion

This is the first trans-Atlantic comparative study of its type, comparing patient characteristic and mortality in two trauma centres. The results should be interpreted in the context of the current development of the two trauma systems [17].

Trauma systems are intended to benefit severely injured patients by implementing comprehensive health care policies throughout a defined catchment region. They aim to improve care at all stages from pre-hospital management through to long-term rehabilitation

Acknowledgements

Sponsorship: Work for this study by Dr. Mullins was supported by grant R49/CCR-006283 from the US Public Health Service, Centers for Disease Control and Prevention, National Center for Injury Prevention and Control, Atlanta, GA. The authors are solely responsible for the contents of the article, and the opinions do not necessarily represent the views of the Centers for Disease Control and Prevention.

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