The Regional Australian Hospital Perspective on Time-to-CT and Associated Outcomes in Trauma Patients: A Retrospective Cohort Study

Abstract

Aim: This study aims to assess the relationship between the time-to-CT and outcomes in trauma patients presenting to a regional Australian hospital. Method: This study is a retrospective analysis of prospectively collected data to review the relationship between time-to-CT and the outcomes of mortality, length of stay, and intrahospital transfer for trauma patients presenting to a single regional Australian hospital between January 2000 and July 2022. Results: There were 127 trauma patients who met the inclusion criteria during the study period. Comparing patients who had a CT performed within 1 h of arrival to patients those who had a CT performed more than 1 h after arrival, there was no statistically significant difference in mortality rate (8.0% vs. 7.7%, p = 1.000), and no statistically significant difference in length of stay (4.5 days vs. 3 days, p = 0.496). Increased age was associated with an increased risk of mortality while First Nations people were found to have a shorter length of stay within hospital. Conclusions: In this cohort study, the time-to-CT was not predictive of increased mortality risk in trauma patients presenting to a regional hospital. The time-to-CT in this regional hospital was comparable to published data from level I trauma centres in Australia. What does this paper add to the literature? This paper is the first to look at the impact of time-to-CT in the regional Australian setting.

1. Introduction

The use of computed tomography (CT) forms an important part of the modern trauma management algorithm in developed countries. Early routine access to CT has been demonstrated to improve survival and decision-making for patients admitted with severe trauma [1,2]. Its ubiquity is such that even small regional facilities within Australia have access to CT and specialist radiology services. As a consequence, CT acts as part of the trauma assessment to determine the severity of injury, the need for and urgency of transfer, or whether the patient can be managed by local hospital staff in consultation with a higher-level trauma centre as part of the expansive trauma network.

Toowoomba Hospital (TBH) is located in the Darling Downs Region of regional Queensland covering a 77,000 square kilometre catchment. It currently operates two CT machines with radiology services available onsite during working hours which are supplemented by external reporting services afterhours.

The rurality and vast areas involved in regional trauma add multiple complexities to trauma management including retrieval logistics and delays in access to investigations, interventions, and high-level care, and offers a different pattern and severity of injuries when compared to metropolitan areas. Rural and remote trauma patients are twice as likely to be hospitalised and nearly twice as likely to die due to the injuries sustained [3]. Road traffic deaths highlight even greater disparity, with nearly 12 times the mortality risk compared to the metropolitan population [4].

Current international guidelines recommend that trauma patients who require imaging should have a CT performed within 1 h of arrival to the hospital. CTs are used as key performance indicators to measure efficient implementation of trauma protocols in the United Kingdom [5,6].

While there are no current standardised Australian guidelines for the time-to-CT in trauma, previous studies have also used the 1 h benchmark. These studies have so far only been conducted in level I trauma centres located within Australian metropolitan areas [7,8]. This study aims to identify whether the time-to-CT is a predictor of outcomes in trauma patients presenting to a regional Australian hospital.

2. Method

2.1. Study Design

This cohort study was a retrospective analysis of prospectively collected data from trauma patients who activated the trauma response system at TBH between 1 January 2000 and 31 July 2022. The criteria to activate the trauma response system at TBH are based on statewide guidelines which include mechanism of injury, physiological criteria, anatomic criteria, and clinician concern.

Data on patient demographics, clinical course, and outcomes were collected from the trauma registry and cross-referenced against handwritten records, electronic medical records, and local radiology services at TBH. The outcomes of concern were mortality rate, length of stay, and intrahospital transfer rate. Mortality was defined as death during acute inpatient admission or within 30 days of discharge either to home or to a rehabilitation service. Length of stay was defined as the number of days of acute inpatient admission including time spent in an intensive care unit, and excluding time spent in a rehabilitation service or subacute unit.

Patients who had a CT performed within 1 h of arrival were assigned to the intervention group. Patients who had a CT performed more than 1 h after arrival were assigned to the comparator group.

2.2. Statistical Analysis

Outcome variables and potential confounders were compared between groups. Variables were assessed for normality visually and with the Shapiro–Wilk test. Continuous variables were summarised as median and interquartile range and were tested between groups using Wilcoxon’s rank-sum test. Categorical variables were summarised as frequences and compared by group using Pearson’s χ² or Fisher’s exact test as appropriate.

Univariable logistic regression was conducted for the binary outcomes of mortality and need for intrahospital transfer. Linear regression with bootstrapping was conducted for the continuous outcome of length of stay. Linearity was assessed using visual and statistical methods. Multivariable analyses were not conducted due to sparse numbers.

Data were analysed with the Stata statistical software package (Stata/SE 18.0 for Windows, StataCorp LLC, College Station, TX, USA). A p-value of <0.05 was considered significant.

3. Results

Between 1 January 2000 and 31 July 2022, 158 adult patients activated the trauma call system at TBH. There were 31 patients excluded who either did not have a CT scan, had a delayed CT scan more than 5 h following arrival, or had a CT scan performed at an external facility prior to arrival. Ultimately 127 eligible trauma patients were included in the study.

Patients were grouped based on whether they had a CT performed within 1 h or a CT performed more than 1 h after arrival to determine the rate of compliance with international guidelines and to facilitate statistical analysis. Overall, there were 88 (69.3%) trauma patients who had a CT performed within 1 h of arrival. The median time-to-CT was 44 min with an interquartile range from 31 min to 62 min. There was no statistically significant difference between the two groups in terms of age, gender, First Nations status, or mechanism of injury (

Table 1. Patient characteristics based on whether CT was performed within 1 h.

Variable		CT Within 1 h N = 88	CT After 1 h N = 39	Total N = 127	p-Value
Age a		39.5 (27–53.5)	36 (24–51)	39 (25–52)	0.210
Gender b	Male	63 (71.6%)	28 (71.8%)	91 (71.7%)
	Female	25 (28.4%)	11 (28.2%)	36 (28.3%)	0.981
First Nations c	No	78 (88.6%)	35 (89.7%)	113 (89.0%)
	Yes	10 (11.4%)	4 (10.3%)	14 (11.0%)	1.000
MOI c	Blunt	71 (80.7%)	32 (82.1%)	103 (81.1%)
	Penetrating	15 (17.0%)	6 (15.4%)	21 (16.5%)
	Burn	2 (2.3%)	1 (2.6%)	3 (2.4%)	1.000

^a Median (IQR) with p-value derived from Wilcoxon’s rank-sum test; N (%) with p-value derived from ^b Pearson’s chi-square or ^c Fisher’s exact test.

).

The overall mortality rate was 7.9%. There was no statistically significant difference in mortality found between the group who had a CT performed within 1 h of arrival and the group who had a CT more than 1 h after arrival (8.0% vs. 7.7%, p = 1.000). Similarly, there was no statistically significant difference in rates of intrahospital transfer to a higher-level trauma centre (20.5% vs. 15.4%, p = 0.501) between the two groups (

Table 2. Summary of outcomes based on whether CT was performed within 1 h.

Outcome		CT Within 1 h N = 88	CT After 1 h N = 39	Total N = 127	p-Value
Mortality a	No	81 (92.0%)	36 (92.3%)	117 (92.1%)
	Yes	7 (8.0%)	3 (7.7%)	10 (7.9%)	1.000
Intrahospital transfer b	No	70 (79.5%)	33 (84.6%)	103 (81.1%)
	Yes	18 (20.5%)	6 (15.4%)	24 (18.9%)	0.501

N (%) with p-value derived from ^a Fisher’s exact test or ^b Pearson’s chi-square test.

).

An analysis of variables using univariable logistic regression demonstrated that age was a statistically significant predictor of mortality (OR 1.061, 95% CI 1.024 to 1.099, p = 0.001). No other variable was found to be predictive of mortality or need for transfer to a higher-level trauma centre (

Table 3. Univariable logistic regression testing variables against mortality and IHT.

Variable		Mortality OR (95% CI)	p-Value	IHT OR (95% CI)	p-Value
Time-to-CT a		1.01 (0.99–1.02)	0.485	0.99 (0.97–1.00)	0.128
CT within 1 h b	No	Ref		Ref
	Yes	1.04 (0.25–4.24)	0.960	1.41 (0.51–3.89)	0.502
Age a		1.06 (1.02–1.10)	0.001	0.99 (0.97–1.02)	0.543
Gender b	Male	Ref		Ref
	Female	1.09 (0.27–4.47)	0.904	1.05 (0.39–2.80)	0.921
First Nations b	No	Ref		Ref
	Yes	(empty)		0.69 (0.14–3.31)	0.642
MOI b	Blunt	Ref		Ref
	Penetrating	(empty)		0.41 (0.09–1.91)	0.256
	Burn	(empty)		1.95 (0.17–22.58)	0.592

Logistic regression performed with variables treated as ^a continuous or ^b categorical; MOI: mechanism of injury; (empty): insufficient data to conduct analysis. IHT: intrahospital transfer.

). An analysis of variables using linear regression demonstrated a statistically significant shorter length of hospital stay in First Nations people (−3.6 days, 95% CI −6.5 to −0.72 days, p = 0.014). No other variable was found to be predictive of length of stay (

Table 4. Linear regression testing variables against LOS.

		Bootstrapped
Variable		Effect (SE)	95% CI	p-Value
Time-to-CT a		−0.025 (0.02)	−0.063, 0.143	0.216
CT within 1 h b	No	Ref
	Yes	1.086 (1.596)	−2.041, 4.215	0.496
Age a		0.001 (0.036)	−0.070, 0.072	0.983
Gender b	Male	Ref
	Female	−1.698 (1.356)	−4.357, 0.960	0.211
First Nations b	No	Ref
	Yes	−3.584 (1.462)	−6.450, −0.718	0.014
MOI b	Blunt	Ref
	Penetrating	−0.440 (1.823)	−4.013, 3.133	0.809
	Burn	6.560 (8.397)	−9.898, 23.018	0.435

Linear regression performed with variables treated as ^a continuous or ^b categorical; LOS: length of stay; MOI: mechanism of injury.

).

4. Discussion

No statistically significant relationship was identified between the primary outcomes and the time-to-CT in trauma patients presenting to TBH. When conducting logistic regression while using time-to-CT as a continuous variable, the confidence intervals are narrow, demonstrating a sample size large enough to ensure an element of precision. However, the true size of effect—if any exists—is likely to be so small that the relationship identified remained statistically insignificant. It would likely require a very large sample size to detect the true effect size if a relationship does exist between time-to-CT and outcomes in trauma patients.

Not unexpectedly, age was found to be a statistically significant predictor of mortality. The analysis found that for every increase of one year of age, the odds of mortality increased by 6.1%. A cross-sectional analysis by Rowh et al. reviewed over 180,000 trauma cases in the United States of America and identified that the largest mortality increase was seen after the age of 69 years [9]. A paper from Wongweerakit et al. found a similar age of 70 years for increased mortality risk when looking at the database of trauma in Thailand [10].

Additionally, First Nations people were found to spend a statistically significantly shorter length of time in hospital compared to non-First Nations people. While not the focus of this study, it was notable that First Nations people spent an average of 3.6 days fewer in hospital compared to non-First Nations people. The cause of this relationship is likely complex and outside the scope of this study; however, it may include factors such as injury severity and discharge against medical advice [11].

A similar study on time-to-CT conducted by Ng et al. at a level I trauma centre in metropolitan Queensland demonstrated a 65.0% rate of trauma patients having CT performed within 1 h of arrival [8]. Another Australian study by Yarad et al. reviewed the time-to-CT at a level I trauma centre in New South Wales and found that the median time-to-CT was 75 min. While the percentage of patients having a CT within 1 h was not published, it can be deduced that it would be less than 50% [7]. Overall, the rate of CT performed within 1 h in TBH was 69.3%, suggesting that the trauma workflow efficiency is comparable to higher-level trauma centres in Australia while acknowledging the likely differences in acuity and injury severity of patients presenting to these centres.

While an Australian standardised guideline for time-to-CT does not exist, it is used as a key performance indicator as part of trauma care verification in Australia and New Zealand [12]. Currently, the published Australian data reference the guidelines used in the United Kingdom by the National Health Service of England (NHS) and the Scottish Trauma Audit Group. Both of these guidelines use the 1 h benchmark as the metric for trauma workflow efficiency. More stringent recommendations are made by the American College of Surgeons, who recommend CT availability within 15 min of arrival at level I and II trauma centres, and within 30 min of arrival at level III trauma centres [13].

Going forward, there should be a move to standardise such guidelines in the context of the Australian experience. The vast areas and remoteness of even some of the larger regional cities means that bespoke recommendations and structures should be implemented to address the unique challenges within the country.

Limitations

The main limitation of this study is its retrospective design. While the data were prospectively collected through the local registry system, the possibility remains of some patients not being captured or incorrect data being recorded due to miscoding. This potential limitation in data collection was mitigated by using several database sources which were cross-referenced to improve accuracy and completeness. One notable limitation was the limited available data on injury severity which were intended to be collected and analysed as a confounding variable. However, the use of scoring systems such as the Injury Severity Score (ISS) or Abbreviated Injury Scale (AIS) or the documentation of a comprehensive trauma survey was not conducted in the majority of cases.

The design of this study also introduces the risk of selection bias in how some patients were prioritised for more urgent or less urgent CT compared to others. Additionally, there would also be other confounders including staffing, workflow, workload, and availability of CT which would have all played a role in the variable of time-to-CT.

The wide historical period used for data collection also introduces temporal bias where there are shifts in treatment paradigms, attitudes or practises, and availability of technologies which would all impact the provided treatment pathways offered to patients at various points in time.

5. Conclusions

In this retrospective study, no statistically significant difference was identified in the primary outcomes of mortality rate, hospital length of stay, and intrahospital transfer rate in trauma patients presenting to a regional Australian hospital. Age and First Nations status were identified as predictors of increased mortality risk and reduced hospital length of stay, respectively. The time-to-CT at TBH appears to be acceptable, with 69.3% of patients receiving CT within 1 h and 75% of patients receiving CT within 62 min. This is in keeping with similar data from level I trauma centres within Queensland. While time-to-CT remains a recommendation and a measurable index of trauma workflow efficiency, this does not appear to be associated with a benefit in the outcomes assessed in this study.