Emergency severity index compared with 4-level triage at the emergency department of Ramathibodi University Hospital

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Abstract

Background

Emergency department (ED) triage is important for categorizing and prioritizing patients. Effective triage may assist in crowd reduction in the ED and appropriate patient management. There are several systems, including the 5-level Emergency Severity Index (ESI) and the 4-level Ramathibodi-nurse triage. Currently, there are limited data by which to compare the 5- versus 4-level triage; particularly on health outcomes, such as length of stay in the ED, mortality, and resource needs.

Objective

To compare the accuracy of 5- and 4-level triage in an ED.

Method

This observational study was conducted on a cross-section of patients in the ED at Ramathibodi Hospital of Mahidol University, Bangkok, Thailand. Eligible patients were those who visited the ED and were evaluated by ESI and nurse triage. Each evaluation was blinded to the results of the other. Discrimination performance between the 5- and 4-level triage was compared by using the area under a receiver operating characteristic (ROC) curve and concordance statistic for prediction of life saving intervention. Net reclassification improvement (NRI) of the 5-level ESI over the 4-level triage was performed.

Result

Study criteria were met by 520 patients. The areas under the ROC curves of the ESI and nurse triage on life-saving intervention were 92.2% (95% confidence intervals were 87.3%, 96.9%) and 81.3% (95% CI 75.2%, 87.3%), respectively. Areas under the ROC curve differed significantly (P < 0.001). The overall reclassification improvement was 42.4%.

Conclusion

The 5-level emergency severity index was more accurate than the 4-level triage in terms of lifesaving intervention.

Triage at the emergency department (ED) is an important process by which to categorize and prioritize patients [1]. Effective triage may assist in crowd reduction in the ED and in appropriate patient management [2-5]. Physician response time to each patient depends on the individual patient category. The triage system was first described by the French physician, Dominique Jean Larrey, during the First World War. It was then developed for use in EDs worldwide [6].

There are several triage systems including the Emergency Severity Index (ESI), Australian Triage Scale, and Manchester Triage System [7, 8]. All triage systems are comparable in terms of effectiveness, but the ESI, widely used in the United States, seems to produce better values for validity, reliability, and inter-rater reliability [9-12]. The latest version of the ESI triage instrument (version 4), has 5 levels as follows: 1—resuscitation, 2—emergency, 3—urgent, 4—less urgent, and 5—non urgent [3].

Ramathibodi Hospital is a major university and tertiary care institution located in central Bangkok, Thailand. All patients in the emergency room are initially evaluated by a triage nurse with years of experience. The nursing triage is divided into 4 levels; critical, emergency, acute, and general. To our knowledge, this triage system has never been fully validated or evaluated. A previous study showed that the 5-level ESI had better sensitivity and specificity than a 3-level version [3]. The sensitivity and specificity increased from 58% to 68% and 83% to 91%, respectively, when the triage was changed from 3 to 5 levels. The under-triage rates were also lower in the 5-level evaluation (12% vs 28%). Currently, there is limited data on directly comparing the 5- and 4-level triage at the ED, particularly on health outcomes such as length of stay in the ED, mortality, or resource needs during an ED visit.

Materials and methods

The study protocol was approved by the Institutional Review Board of Mahidol University (approval No. MURA2014/414). This observational study was conducted on a cross-section of patients inthe ED in Ramathibodi Hospital, Mahidol University, Thailand. Eligible patients were patients who visited the ED and were evaluated by both the ESI (version 4), or 5-level ESI and the nurse triage. The ESI was performed by the emergency physicians on duty at the ED, while the nurse triage was evaluated by an ED nurse with at least 5 years of experience at the ED. Each evaluation was blinded to the results of the other. We excluded patients with incomplete medical data, referred patients, patients using the emergency medical service (EMS), and patients with appointments for vaccination or medications. Written informed consent to participate in the present study was given by all included patients or their nearest relatives.

Baseline characteristics of all patients were recorded. Additionally, 5 outcomes were evaluated including immediate life-saving intervention (LSI) (Table 1), resource needs, hospitalization rate, mortality rate, and length of stay at the ED.

Table 1

Immediate life-saving interventions at the emergency department*

Life-savingNot life-saving
Airway /breathingΒVM ventilationOxygen administration
IntubationNasal cannula
Surgical airwayNon-rebreather
Emergency continuous positive airway pressure
Emergency bilevel positive airway pressure
Electrical therapyDefibrillationCardiac monitor
Emergency cardioversion
External pacing
ProceduresChest needle decompressionDiagnostic Test
Pericardiocentesis- Electrocardiography
Open thoracotomy- Laboratory test values
Intraosseous access- Ultrasound
- Focused abdominal scan for trauma
HemodynamicsSignificant intravenous fluid resuscitationIntravenous access
Blood administration
Control of major bleedingSaline lock for medications
MedicationsNaloxoneAcetylsalicylic acid
Intravenous 50% dextroseIntravenous nitroglycerine
DopamineAntibiotics
AtropineHeparin
AdenocardPain medications
Respiratory treatments with beta agonists

Resource needs were defined by any investigations or treatments required during the ED visit (Table 2).

Table 2

Resource needs at the emergency department

Resource needsNo resource need
Laboratory test values (blood, urine)History, physical
Electrocardiography, X-ray imaging, computed tomography, magnetic resonance imaging, ultrasound angiographyPoint-of-care testing
Intravenous fluids (hydration)Saline or heparin lock
Intravenous fluids, intramuscular, or nebulized medicationsPer oral medications
Tetanus immunization
Prescription refills
Specialty consultationPhone call to primary care physician
Simple procedure = 1 (Laceration repair, Foley catheter)Simple wound care (dressings, recheck)
Complex procedure = 2 (conscious sedation)Crutches, splints, slings

Sample size calculation

The sample size was calculated using the formula for cluster surveys. Based on the prevalence of patient category 2 of 3% in 2013, the population size of 1,000,000, and the confidence interval of 95%, 497 patients were required.

Statistical analyses

Descriptive statistics were used to describe patients’ characteristics. Discrimination performance between the 5- and 4-level triage was compared by using the area under a receiver operating characteristic (ROC) curve and concordance statistic on prediction of life saving intervention. Net reclassification improvement (NRI) of the 5-level ESI (version 4) over the 4-level triage was executed based on 2 categories of reclassification improvement (RI) according to LSI: RILSI for users and RInon-LSI for

nonusers. The RI for users of LSI was the proportion of patients who were categorized at a higher level by the 5-level ESI than by the 4-level triage minus the proportion of patients who were categorized at a lower level by the ESI than by the 4-level triage. The RI for nonusers of LSI was the proportion of patients who were categorized at a lower level by the ESI than by the 4-level triage minus the proportion of patients who were categorized at a higher level by the ESI than by the 4-level triage. The NRI was the sum value of RILSI and RInon-LSI

Results

During the 4 month period of the study, there were 11,312 patients who visited the ED. Of those, 560 patients (4.95%) met the study criteria, of whom 40 were excluded because of incomplete data (25). because they were referred patients (10), or because they were patients using EMS (5). In total, data from 520 patients were included in the analysis. The characteristics of these patients are shown in Table 3. None of the patients were defined as category 4 by the nurse triage because this category was one of the exclusion criteria.

Table 3

Characteristics of patients visiting the ED who underwent both ESI and nursing triage assessment

FactorsNumbers (percentage) or median (range)
Male sex216 (41.5%)
Age, years51 (0.4-97)
Trauma93 (17.9)
Final status
 Discharge441 (84.8)
 Admitted50 (9.6)
 Operative room11 (2.1)
 Referred14 (2.7)
 Refused treatment3 (0.58)
 Death1 (0.19)
Resource needs
 None97 (18.7)
 1116 (22.3)
 ≥2307 (59.0)
Life-saving intervention32 (6.2)
Nursing triage (4 level)
 18 (1.5)
 2180 (34.6)
 3332 (63.9)
 40
ESI triage (5 level)
 114 (2.7)
 292 (17.7)
 3225 (43.3)
 4116 (22.3)
 573 (14.0)
Length of stay in ED, hours2.54 (0.25-169)
Death2 (0.38)
ESI, Emergency Severity Index; ED, emergency department

Characteristics of patients by the 4-level nurse triage

The majority of patients were classified as class 2 emergency and 3 urgency (512 patients; 98.5%). The median time for length of stay in the ED was higher for class 1 (9.5 h) than for class 2 or 3. There were 307 patients who required more than 2 resources (59.0%) and 32 patients (6.2%) needed LSI. mostly in class 1 (62.5%). Two patients in class 2 and 3 died. The details are shown in Table 4.

Table 4

Characteristics of patients by the 4-level nurse triage

FactorsCategory

1 Critical (n = 8)2 Emergency (n = 180)3 Urgent (n = 332)
Median ED length of stay (range), hours9.50 (0.75-153)3.94 (0.5-169)2 (0.25-124)
Resource needs
None013 (7.2%)84 (25.3%)
 1027 (15.0%)89 (26.8%)
 ≥28 (100%)140 (77.8%)159 (47.9%)
Final status
 Discharged2 (25%)143 (79.4%)315 (94.9%)
 Admitted to wards5 (63%)23 (12.8%)14 (4.2%)
 Admitted to ICU1 (13%)14 (7.8%)3 (0.9%)
Life-saving intervention
 Users (n= 32)5 (63%)24 (13%)3 (0.9%)
Death01 (0.6%)1 (0.3%)
ED: emergency department; ICU: intensive care unit

Characteristics of patients by the ESI (Table 5)

Table 5

Characteristics of all patients by ESI triage

FactorsClassifications

1 (n = 14)2 (n = 64)3 (n = 205)4 (n = 114)5 (n = 73)
Median ED length of stay (range), hours4.838.673.411.620.86
(0.75-153.5)(0.5-169)(0.5-124)(0.41-34.17)(0.25–4)
Resource needs
 None02 (2%)14 (6%)17 (15%)64 (88%)
 105 (5%)32 (14%)71 (61%)8 (11%)
 ≥214 (100)85 (92%)179 (80%)28 (24%)1 (1%)
Final status
 Discharged4 (29%)64 (69%)205 (91%)114 (99%)73 (100%)
 Admitted to wards3 (21%)20 (22%)17 (8%)2 (2%)0
 Admitted to ICU7 (50%)8 (9%)3 (1%)00
Life-saving intervention
 Users (n= 32)13 (93%)17 (19%)2 (1%)00
Death20000
ESI: Emergency Severity Index, ED: emergency department, ICU: intensive care unit

The majority of patients were classified as class 3 (205 patients; 39.4%). The median time for length of stay in ED was highest in class 2. There were 32 patients (6.2%) who needed lifesaving procedures. These patients were only in classes 1-3. Two patients who died were classified as class 1.

Comparison between the triage by nurses and ESI by LSI

Discrimination performance

The areas under the ROC curves of the triage by ESI and nurses on LSI were significantly different (P <0.001) (Figure 1).

Figure 1
Figure 1

The receiver operating characteristic curves showed the use of life saving intervention when using the 5-level Emergency Severity Index triage (triangles unbroken line; AUC 92.2%; 95% CI 87.3%, 96.9%) versus the 4-level or nurse triage (squares dashed line; area under the curve (AUC) = 81.3%; 95% CI 75.2%, 87.3%). ROC AUCs were significantly different at a level of P < 0.001

Citation: Asian Biomedicine 10, 2; 10.5372/1905-7415.1002.477

Net reclassification improvement

The concordant and disconcordant numbers of patients by the nurse and ESI triage categorized by LSI are shown in Table 6.

Among the group using an LSI (32 patients). 9 patients, who had been classified by the nurse triage, were reclassified to a higher class by the ESI and 1 patient was reclassified to a lower class. The reclassification improvement was (9-1) /32 or 25%.

For those who did not receive lifesaving intervention (488 patients), 15 patients who had been classified by the nurse triage were reclassified to a lower class by the ESI and 100 patients were reclassified to a lower class. The reclassification improvement was (100-15) /488 or 17.4%. The net reclassification improvement was 42.4% (95%CI 0.226,0.622).

Discussion

This study showed that the 5-level ESI triage is more accurate than the 4-level assessment tool used by nurses at Ramathibodi Hospital to predict the necessity for LSI. The 5-level tool had better discriminatory performance (Figure 1) and reclassification improvement (Table 6) than that of the 4-level tool.

The larger area under the ROC curve by the ESI (92.2% vs 81.3%) indicated the greater accuracy of the 5-level assessment tool to predict the necessity for life-saving intervention over the 4-level tool (Figure 1). Ahead-to-head comparison of both tools showed that 68.8% in the life-saving-intervention group and 76.4% in the non-life-saving-intervention group were concordant. However, the net benefit for reclassification improvement was 42.4% (95%CI: 0.226, 0.622). These results implied that 42.4% of patients may be either overrated or under-rated by the 4-level tool compared with the ESI in predicting the occurrence of serious life-saving intervention. Also of note was that the 2 patients who died were correctly identified by the ESI as class 1, while the 4-level categorized them as class 2 or 3.

New information regarding assessment of severity in the ED by this study included (1) a comparison of the 5-level versus 4-level triage (previous studies reported on the 5-level versus 3-level [3], (2) the accuracy of the 5-level ESI (previous studies showed reliability and validity, but not accuracy [9, 12], (3) additional outcomes (previous studies showed correlation of the ESI and several outcomes such as survival, resource use, and length of stay at the ED, but the not life-saving intervention [14-16],

There were some limitations to this study. First, each tool was used by a different group of assessors. The 4-level triage was performed by nurses in the ED and the ESI was conducted by emergency department physicians. Nevertheless, the nurses who performed the triage were experienced. Second, patients enrolled in the study were all general patients at the ED, not a specific study population such as trauma or elderly patients [13,17]. Third, the outcome was primarily focused only on life-saving intervention because of the low mortality rate (0.38%). Finally, the study was conducted at the ED of a university hospital. The results may not apply to all hospitals, such as primary care hospitals. Further studies are needed to examine the effects in specific study populations and other hospital settings.

Table 6

Reclassification improvement of receivers and non-receivers of life-saving interventions (LSI) and net reclassification improvement

LSIuse4 level triageESI triageTotal

Level 3Level 2Level 1
YesLevel 32013
Level 2016824
Level 10145
Total2171332
Reclassification improvementLSI = (9-1) /32 = 0.250
NoLevel 3314150329
Level 298580156
Level 10213
Total412751488
Reclassification improvementnon-LSI = (100-15) /488 = 0.174
Net reclassification improvement (NRI) = 0.424 (95% CI: 0.226, 0.622) (P <0.001)

Conclusion

The 5-level emergency severity index is more accurate than 4-level triage in terms of life-saving intervention.

Acknowledgements

The authors thank Mr. Dylan Southard, Research Affairs, Faculty of Medicine, Khon Kaen University, Thailand, for his English language editing of the manuscript. This study was supported by TRF Senior Research Scholar Grant from the Thailand Research Fund (TRF grant No. RTA5880001), and the Higher Education Research Promotion and National Research University Project of Thailand, Office of the Higher Education Commission, Thailand, through the Health Cluster (SHeP-GMS), Khon Kaen University and Thailand Research Fund (IRG 5780016).

Conflict of interest statement: The authors declare that there is no conflict of interest in this research.

References

  • 1

    Wuerz RC Milne LW Eitel DR Travers D Gilboy N. Reliability and validity of a new five-level triage instrument. Acad Emerg Med. 2000; 7:236-42.

    • Crossref
    • Export Citation
  • 2

    Murray M Bullard M Grafstein E; for the CTAS and CEDIS National Working Groups. Revisions to the Canadian Emergency Department Triage and Acuity Scale Implementation Guidelines. CJEM. 2004; 6: 421-7.

    • Crossref
    • Export Citation
  • 3

    Travers DA Waller AE Bowling JM Flowers D Tintinalli J. Five-level triage system more effective than three-level in tertiary emergency department. J Emerg Nurs. 2002; 28:395-400.

    • Crossref
    • Export Citation
  • 4

    Jelinek GA Little M. Inter-rater reliability of the National Triage Scale over 11500 simulated occasions of triage. Emerg Med. 1996; 8:226-30.

  • 5

    Beveridge R Ducharme J Janes L Beaulieu S Walter S. Reliability of the Canadian emergency department triage and acuity scale: interrater agreement. Ann Emerg Med. 1999; 34:155-9.

    • Crossref
    • Export Citation
  • 6

    Richardson D. No relationship between emergency department activity and triage categorization. Acad Emerg Med. 1998; 6:141-5.

  • 7

    Downey LV Zun LS Burke T. Comparison of Canadian triage acuity scale to Australian Emergency Mental Health Scale triage system for psychiatric patients. Int Emerg Nurs. 2015; 23:138-43.

    • Crossref
    • Export Citation
  • 8

    Canadian Association of Emergency Physicians. Canadian Emergency Department Triage and acuity scale implementation guidelines. J Can Assoc Emerg Phys. 1999; 1:S1-16.

  • 9

    Wurez RC Milne LW Eitel DR Travers D Gilboy N. Reliability and validity of a new five-level triage instrument. Acad Emerg Med. 2000; 7236-2.

  • 10

    Wurez RC Travers D Gilboy N Eitel DR Rosenau A Yazhari R. Implementation and refinement of the emergency severity index. Acad Emerg Med. 2001; 8: 170-6.

    • Crossref
    • Export Citation
  • 11

    ESI Triage Study Group Wurez R. Emergency severity index triage category is associated with six-month survival. Acad Emerg Med. 2001; 8:61-4.

  • 12

    Tanabe P Travers D Rosenau A Gilboy N Wuerz R. The Emergency Severity Index Triage algorithm version 2 is reliable and valid. Acad Emerg Med. 2003; 10:1070-80.

    • Crossref
    • Export Citation
  • 13

    Platts-Mills TF Travers D Biese K McCall B Kizer S La Mantia Busby JW Cairns CB. Accuracy of the Emergency Severity Triage instrument for identifying elder emergency department patients receiving an immediate life-saving intervention. Acad Emerg Med. 2010; 17:238-43.

    • Crossref
    • Export Citation
  • 14

    Chi CJ Huang CM. Comparison of the Emergency Severity Index (ESI) and the Taiwan Triage System in predicting resource utilization. J Formos Med Assoc. 2006; 105:617-25.

    • Crossref
    • Export Citation
  • 15

    Wuerz R. Emergency Severity Index triage category is associated with six-month survival. ESI triage study group. Acad Emerg Med. 2001; 8:61-4.

  • 16

    Grossman FF Nickel CH Christ M Schneider K Spirig R Bingisser R. Transporting clinical tools to new settings: Cultural adaptation and validation of the Emergency Severity Index in German. Ann Emerg Med. 20711; 57:257-64.

  • 17

    Storm-Versloot MN Ubbink D T Kappelhof J Luitse JSK. Comparison of an informally structured triage system the emergency severity index and the Manchester triage system to distinguish patient priority in the Emergency Department. Acad Emerg Med. 2011; 18:822-9.

    • Crossref
    • Export Citation

Footnotes

*Adapted from [13].

If the inline PDF is not rendering correctly, you can download the PDF file here.

  • 1

    Wuerz RC Milne LW Eitel DR Travers D Gilboy N. Reliability and validity of a new five-level triage instrument. Acad Emerg Med. 2000; 7:236-42.

    • Crossref
    • Export Citation
  • 2

    Murray M Bullard M Grafstein E; for the CTAS and CEDIS National Working Groups. Revisions to the Canadian Emergency Department Triage and Acuity Scale Implementation Guidelines. CJEM. 2004; 6: 421-7.

    • Crossref
    • Export Citation
  • 3

    Travers DA Waller AE Bowling JM Flowers D Tintinalli J. Five-level triage system more effective than three-level in tertiary emergency department. J Emerg Nurs. 2002; 28:395-400.

    • Crossref
    • Export Citation
  • 4

    Jelinek GA Little M. Inter-rater reliability of the National Triage Scale over 11500 simulated occasions of triage. Emerg Med. 1996; 8:226-30.

  • 5

    Beveridge R Ducharme J Janes L Beaulieu S Walter S. Reliability of the Canadian emergency department triage and acuity scale: interrater agreement. Ann Emerg Med. 1999; 34:155-9.

    • Crossref
    • Export Citation
  • 6

    Richardson D. No relationship between emergency department activity and triage categorization. Acad Emerg Med. 1998; 6:141-5.

  • 7

    Downey LV Zun LS Burke T. Comparison of Canadian triage acuity scale to Australian Emergency Mental Health Scale triage system for psychiatric patients. Int Emerg Nurs. 2015; 23:138-43.

    • Crossref
    • Export Citation
  • 8

    Canadian Association of Emergency Physicians. Canadian Emergency Department Triage and acuity scale implementation guidelines. J Can Assoc Emerg Phys. 1999; 1:S1-16.

  • 9

    Wurez RC Milne LW Eitel DR Travers D Gilboy N. Reliability and validity of a new five-level triage instrument. Acad Emerg Med. 2000; 7236-2.

  • 10

    Wurez RC Travers D Gilboy N Eitel DR Rosenau A Yazhari R. Implementation and refinement of the emergency severity index. Acad Emerg Med. 2001; 8: 170-6.

    • Crossref
    • Export Citation
  • 11

    ESI Triage Study Group Wurez R. Emergency severity index triage category is associated with six-month survival. Acad Emerg Med. 2001; 8:61-4.

  • 12

    Tanabe P Travers D Rosenau A Gilboy N Wuerz R. The Emergency Severity Index Triage algorithm version 2 is reliable and valid. Acad Emerg Med. 2003; 10:1070-80.

    • Crossref
    • Export Citation
  • 13

    Platts-Mills TF Travers D Biese K McCall B Kizer S La Mantia Busby JW Cairns CB. Accuracy of the Emergency Severity Triage instrument for identifying elder emergency department patients receiving an immediate life-saving intervention. Acad Emerg Med. 2010; 17:238-43.

    • Crossref
    • Export Citation
  • 14

    Chi CJ Huang CM. Comparison of the Emergency Severity Index (ESI) and the Taiwan Triage System in predicting resource utilization. J Formos Med Assoc. 2006; 105:617-25.

    • Crossref
    • Export Citation
  • 15

    Wuerz R. Emergency Severity Index triage category is associated with six-month survival. ESI triage study group. Acad Emerg Med. 2001; 8:61-4.

  • 16

    Grossman FF Nickel CH Christ M Schneider K Spirig R Bingisser R. Transporting clinical tools to new settings: Cultural adaptation and validation of the Emergency Severity Index in German. Ann Emerg Med. 20711; 57:257-64.

  • 17

    Storm-Versloot MN Ubbink D T Kappelhof J Luitse JSK. Comparison of an informally structured triage system the emergency severity index and the Manchester triage system to distinguish patient priority in the Emergency Department. Acad Emerg Med. 2011; 18:822-9.

    • Crossref
    • Export Citation
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    The receiver operating characteristic curves showed the use of life saving intervention when using the 5-level Emergency Severity Index triage (triangles unbroken line; AUC 92.2%; 95% CI 87.3%, 96.9%) versus the 4-level or nurse triage (squares dashed line; area under the curve (AUC) = 81.3%; 95% CI 75.2%, 87.3%). ROC AUCs were significantly different at a level of P < 0.001

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