Original Contribution

Correlation of the Canadian Pediatric emergency triage and Acuity Scale to ED resource utilization

Warren Ma MD^a, Amiram Gafni PhD^b, Ran D. Goldman MD^a,?

^aPediatric Research in Emergency Therapeutics (PRETx) Program, Division of Pediatric Emergency Medicine, Department of Pediatrics, British Columbia Children’s Hospital, Child and Family Research Institute,

University of British Columbia, Vancouver, British Columbia, Canada V6H 3V4

^bThe Centre for Health Economics and Policy Analysis, Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada L8S 4L8

Abstract

Objectives: The aim of this study was to find if there is a correlation between acuity measured by the Canadian Pediatric Emergency Triage and Acuity Scale (Ped-CTAS) and resource utilization in a large tertiary academic emergency department (ED). If correlation exists, it may indicate that resource allocation was done in accordance with needs (the more acute the patient, the more resources needed). This may also be the basis for future consideration regarding resource allocation decisions.

Methods: All pediatric patients (0-19 years of age) who were seen in the ED during 12 randomly selected days between May 1, 2005, and April 30, 2006, were included in the study. Detailed information regarding number and types of investigations ordered was collected. To look at the aggregate use of resources, we used the unit of cost. Resource utilization was calculated using standardized cost lists, and results were used to explore the correlation between different Ped-CTAS levels and resource utilization. A fixed cost model was used to predict the remainder of costs, other than diagnostic services.

Results: Of the 1661 patients presenting during the study period, 1618 (97.4%) were included in the study. The mean laboratory, microbiology, imaging, and total investigational costs increased with increasing acuity. This difference was insignificant between the semiurgent and the nonurgent categories of the Ped-CTAS.

Conclusions: The Ped-CTAS level correlates well with resource utilization for patient management in the ED. Further research should focus on measuring nursing and physician time use for each Ped-CTAS level to more accurately document ED resource utilization.

(C) 2008

Introduction

Emergency departments (EDs) have experienced a significant increase in patient visits, resulting in increasED wait times and overcrowding recently [1-4]. Efficient, safe,

* Corresponding author.

and responsible operation of ED uses triage to promote rapid identification of patients with urgent life-threatening condi- tions to implement proper and timely management and ensure that all patients are seen based on their acuity [5-7]. The Canadian Emergency Department Triage and Acuity Scale (CTAS), which has the endorsement of the Canadian Association of Emergency Physicians, the National Emer- gency Nurses Affiliation, and L’association des medecins

0735-6757/$ – see front matter (C) 2008 doi:10.1016/j.ajem.2008.02.024

d’urgence du Quebec [5,6], was nationally implemented in October 1999 and revised in 2003. It is based on the Australasian National Triage Scale [8,9], with Canadian modifications. The Canadian Pediatric Emergency Triage and Acuity Scale (Ped-CTAS) was developed in conjunction with the Canadian Pediatric Society, to account for age, develop- mental stage, acuity, family dynamics, cultural, and social variables that are important in the pediatric population [10]. Although not originally designed to serve as such, if Ped-CTAS correlates well with resource utilization of diagnostics in the ED, it may serve as a tool to indicate that resources are allocated according to acuity (ie, need) but can potentially be the baseline to the development of tools to more accurately predict future utilization. Initial studies show that CTAS can predict admission rates, hospital length of stay, and diagnostic utilization, as well as ED length of stay and blood tests [11-15]. A recent study on the validity of an electronic version of CTAS (not pediatric CTAS) did show significant correlation to total inpatient and ED cost [16]. We are unaware of additional studies that specifically compared a patient’s triage score with ED resource utilization of diagnostic services. Although few papers examined ED cost analysis, they did not draw any conclusions regarding resource utilization correlation to patient acuity [17-20]. A small number of previous studies have shown correlation between Ped- CTAS and admission rates, ED length of stay, and ED investigational rates [15,21]. With increased utilization of EDs and a growing focus placed on efficient use of available resources, the role of Ped-CTAS in planning

resource allocation may increase.

Our aim was to determine the correlation between costs of resource utilization in the ED with respect to Ped-CTAS in a large tertiary academic center in Canada.

Methods

Study design and setting

This retrospective study was carried out in the ED of The Hospital for Sick Children in Canada, a university-affiliated pediatric tertiary care hospital with approximately 50 000 annual ED patient visits. Staff at the ED consists of pediatric emergency physicians, subspecialty fellows, residents, medical students, and registered nurses. Triage nurses, who have all received standardized formal training in the use of Ped-CTAS, completed the Ped-CTAS evaluations.

Study participants

The selected study period consisted of 12 randomly selected days, 1 day per month, between May 1, 2005, and April 30, 2006. Each day, 00:00 to 23:59, was selected using a random number generator (“RANDBETWEEN(X,Y); Microsoft Office Excel 2003). All patients (0-19 years of

age) who registered at the ED during the selected study days were included. This study received ethics approval from the institutional research board.

Data collection

The primary outcome measure was the ED cost of diagnostic resource utilization, as measured by cost of laboratory, microbiology, and imaging tests in the ED. We decided to compare the acuity with all services together to allow a general context of running a clinical department.

A single investigator (W.M.) collected all the data retrospectively from the hospital “Electronic Patient Chart” computerized database. Emergency department records, laboratory results, and diagnostic Imaging results were reviewed. The data were entered and organized in Microsoft Office Excel 2003 workbooks and spreadsheets. Detailed information on the number and types of all investigations ordered in the ED was collected.

Data analysis

All data analysis was completed using SPSS v 14.0 for Windows (SPSS Inc). There were only 6 cases of Ped-CTAS 1, resuscitation, so these cases were combined with Ped- CTAS 2 cases for statistical analysis.

Cost determination

Laboratory and microbiology investigational costs were calculated using rates obtained from the Ontario Ministry of Health schedule of benefits for outsourced laboratory services [22]. Imaging costs were calculated from the diagnostic radiology section of the master schedule of benefits obtained from the Ontario Ministry of Health [23]. Both the technical and interpretive components of radi- ological examinations were included. For Computerized tomography examination, the average of a non- contrast CT of the head, CT of the abdomen, and CT of the pelvis was used. X-rays were broken down to extremity and nonextremity (eg, chest or abdominal x-rays) x-ray costs. For nonextremity x-rays, the average cost of 2 views of the chest and 3 views of the abdomen was used. For extremity x-rays, the average cost of 3 views of the cervical spine, 3 views of the shoulder, 2 views of the elbow, 2 views of the hands, 2 views of the wrist, 2 views of the ankle, and 2 views of the foot was used.

To calculate Total costs, we used a fixed cost model for nursing care at 2 nursing hours per patient with an average cost of $35/h (Canadian currency), support staff costs (ie, unit clerks, registration clerks, and respiratory technicians) were estimated at $15 per patient, and medical supplies including medications were estimated at $15 per patient. This meant that for each patient, an additional $100 was added to the investigational costs. Emergency department

Fig. 1 Study flow chart.

physician remuneration was not included in this analysis because it is payable by a separate single party payer other than the hospital.

Results

Ped-CTAS specific demographics

Of a total 52 490 children registered at the ED during the study period, a total of 1618 records were included in

Table 1 Pediatric CTAS levels and demographics

the analysis (Fig. 1). Table 1 shows the demographic distribution of the study population. There were no significant differences in sex or language spoken at home between the different Ped-CTAS triage groups. The older the patient, the higher the acuity as registered by the nurses using Ped-CTAS. There were significant differ- ences between Ped-CTAS groups and the chief complaints at presentation. Infectious complaints represented most of the complaints in all triage categories. There was an increased frequency of medical problems, major trauma, and surgical complaints with increasing triage acuity. There was an increased frequency of minor trauma with decreasing frequency.

Laboratory, microbiology, and imaging investigation costs

The mean laboratory costs within the Ped-CTAS levels are shown in Table 2. Notably, there was a 49- and 24-fold difference between the mean laboratory costs per patient in the resuscitation-emergent and urgent category, respec- tively, compared with the nonurgent category. Overall, mean laboratory costs increased with increasing acuity. This trend was also true for mean microbiology costs, which also increased with increasing acuity (Table 2). Finally, mean imaging costs also increased with increasing acuity (Table 2).

Total costs

Mean total diagnostic costs showed a 17-fold difference between the resuscitation-emergent category and the non- urgent category. Overall, the mean diagnostic costs increased with increasing acuity (Table 2). Mean total care

Resuscitation and Urgent Semiurgent Nonurgent Total P value emergent (n = 161) (n = 776) (n = 628) (n = 53) (n = 1618)
Sex
Female	67	(42)	330	(42.5)	280	(45)	21	(40)	698	(43)
Male	94	(58)	446	(57.5)	348	(55)	32	(60)	920	(57)	.783
Language
English	143	(89)	715	(92)	573	(91)	49	(93)	1480	(92)
Other	12	(7)	47	(6)	40	(6)	3	(5)	102	(6)
Not available	6	(4)	14	(2)	15	(3)	1	(2)	36	(2)	.812
Mean age (mo)	80		64		61		59		64
Chief complaint
Infectious	55	(34)	368	(47)	331	(53)	27	(51)	781	(48)
Medical	57	(35)	233	(30)	114	(18)	7	(13)	411	(25)
Minor trauma	13	(8)	91	(12)	151	(24)	16	(30)	271	(17)
Major trauma	17	(11)	28	(4)	1	(0.2)	0	(0)	46	(2.8)
Surgical	11	(7)	27	(4)	10	(2)	1	(2)	49	(3)
Other	8	(5)	29	(4)	21	(3)	2	(4)	60	(4)
Values are presented as n (%), except where noted.

Resuscitation and Urgent Semiurgent Nonurgent Overall emergent (n = 161) (n = 776) (n = 628) (n = 53) mean (n = 1618)
Laboratory costs	62.37	(48.73)	30.18	(23.58)	9.41	(7.35)	1.28 (1)	23.38
Microbiology costs	7.20	(5.76)	5.55	(4.44)	2.57	(2.06)	1.25 (1)	4.42
Imaging costs	29.70	(9.11)	15.61	(4.79)	7.03	(2.16)	3.26 (1)	13.28
Total diagnostic costs	99.27	(17.15)	51.35	(8.87)	19.02	(3.28)	5.79 (1)	42.07
Mean total ED costs	199.27		151.35		119.02		105.79	142.07
Values inside parentheses are ratio to nonurgent.

costs are as listed in Table 2 and are $100 above the total diagnostic costs (Fig. 2).

Table 2 Pediatric CTAS levels and mean costs of diagnostic interventions (in Canadian dollars)

Limitations

This study has several limitations. First, it is a retro- spective study with a potential to have missing data and with reliance on the quality of the reported data. However, the large sample size and the randomization of the chart selection should help reduce bias. We could not differentiate between Ped-CTAS levels 1 and 2, but a larger sample will be able to overcome this limitation. Furthermore, we assumed that the Ped-CTAS levels assigned by triage nurses did not suffer from interrater differences between different nurses. Pre- vious studies have shown good interrater reliability for Ped- CTAS [24,25]. Also, the use of a fixed cost model for estimation of nursing staff costs and support staff costs does not allow for variances of nursing costs associated with various ED lengths of stay and acuity. The fixed cost model was chosen because it is currently the system upon which nursing staffing needs are calculated, and there are some previous reports of using fixed nursing costs in ED cost analysis [26,27]. Future research should focus on determin- ing time spent by nurses and physicians for patients in each Acuity level, to more accurately determine resource utiliza- tion. Our clinical experience suggests that the higher the acuity, the more time nurses and physicians need to spend with the patient. If this is documented, it will even further support the findings of this study. Furthermore, we do not analyze costs such as building maintenance and utilities associated with running an ED; however, these costs will always be present regardless of patient acuity or volume. Lastly, there is limited generalizability to our findings. The ED being examined functions under a single payer system in a nonprofit hospital. This may be different from the multipayer for-profit models found in other jurisdictions. Additional studies of similar design in different ED settings may increase the generalizability of our findings.

Discussion

We found that higher-acuity Ped-CTAS is associated with higher costs of resource utilization of diagnostic

services in our ED. There was a higher total investigational cost and, subsequently, cost of patient management in the ED. This is important because it may allow Ped-CTAS to be used as a tool to indicate resource allocation in the ED and, in the future, to potentially serve as a basis to planning allocation.

The results of this study show that Ped-CTAS correlates well with laboratory investigational costs, where acute Ped- CTAS categories exhibited higher costs. The absence of a strong association between acuity and cost of microbiology investigation can be explained by the increasing frequency of trauma in higher-acuity categories and decreased need for microbiological investigations. A strong correlation also exists between increased acuity and increased cost of imaging. These findings can allow administrators to use Ped-CTAS case mix to more accurately plan funding for EDs. Administrators may use this validated triage tool as a

Fig. 2 Total care cost per CTAS category (Canadian currency).

basis of comparison between planning patterns of various hospitals or regions. These findings also help further validate Ped-CTAS as an accurate triage tool.

Other studies have been conducted to look at the Predictive ability of 5-level triage scales such as the Emergency Severity Index and CTAS [11-14,28]. These studies have previously used blood investigation and imaging rates as markers for investigational resource utilization in the validation of CTAS [11,12,14]. One recent study does describe an association between triage scores and cost [16]. Additional cost analysis research regarding ED operations has focused mainly on economic models that describe ED operations and is not specific to cost differences between different triage levels [17-20].

It has previously been demonstrated that Ped-CTAS correlates well to hospitalization rates, ED length of stay, and investigational rates [15]. However, to our knowledge, no studies have examined the correlation between Ped-CTAS and cost. The strength of our study is that we incorporate all investigations, including laboratory, microbiology, and imaging for each patient, and calculate total costs for each patient. With such detailed data, we are able to determine mean costs per patient in each Ped-CTAS category and compare means. This allows us to draw strong conclusions regarding cost variance between Ped-CTAS categories. This strong correlation may allow administrators to use Ped- CTAS case mix to more accurately plan financial aspects of ED operations.

Conclusions

Based on the study results, patient’s Ped-CTAS levels correlates well for ED diagnostic costs and, ultimately, total resource utilization in the ED.

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