Validity and reliability of the South African Triage Scale in prehospital providers

Nee-Kofi Mould-Millman,Jennifer L Pigoga,Julia M Dixon,Michael Lee,Lee A Wallis,Shaheem De Vries,Maxene Meier,Chandni Patel,Kubendhren Moodley,Taylor Burkholder,Kathryn Colborn

doi:10.1186/s12873-021-00406-6

Abstract

BackgroundThe South African Triage Scale (SATS) is a validated in-hospital triage tool that has been innovatively adopted for use in the prehospital setting by Western Cape Government (WCG) Emergency Medical Services (EMS) in South Africa. The performance of SATS by EMS providers has not been formally assessed. The study sought to assess the validity and reliability of SATS when used by WCG EMS prehospital providers for single-patient triage.MethodsThis is a prospective, assessment-based validation study among WCG EMS providers from March to September 2017 in Cape Town, South Africa. Participants completed an assessment containing 50 clinical vignettes by calculating the three components — triage early warning score (TEWS), discriminators (pre-defined clinical conditions), and a final SATS triage color. Responses were scored against gold standard answers. Validity was assessed by calculating over- and under-triage rates compared to gold standard. Inter-rater reliability was assessed by calculating agreement among EMS providers’ responses.ResultsA total of 102 EMS providers completed the assessment. The final SATS triage color was accurately determined in 56.5%, under-triaged in 29.5%, and over-triaged in 13.1% of vignette responses. TEWS was calculated correctly in 42.6% of vignettes, under-calculated in 45.0% and over-calculated in 10.9%. Discriminators were correctly identified in only 58.8% of vignettes. There was substantial inter-rater and gold standard agreement for both the TEWS component and final SATS color, but there was lower inter-rater agreement for clinical discriminators.ConclusionThis is the first assessment of SATS as used by EMS providers for prehospital triage. We found that SATS generally under-performed as a triage tool, mainly due to the clinical discriminators. We found good inter-rater reliability, but poor validity. The under-triage rate of 30% was higher than previous reports from the in-hospital setting. The over-triage rate of 13% was acceptable. Further clinically-based and qualitative studies are needed.Trial registrationNot applicable.

Highlights

The South African Triage Scale (SATS) is a validated in-hospital triage tool that has been innovatively adopted for use in the prehospital setting by Western Cape Government (WCG) Emergency Medical Services (EMS) in South Africa
Use of clinical discriminators had relatively worse agreement, both within EMS providers (k = 0.59) and when EMS providers were compared to gold standard (k = 0.49). These findings suggest that EMS providers, as a cohort, use this triage tool fairly inconsistently compared to in-hospital providers, but use it consistently within themselves – we should note that the EMS providers generated incorrect triage scores 43% of the time, as a cohort, due to incorrect calculation of triage early warning score (TEWS) and/or misapplication of the clinical discriminators
This study was the first assessment of validity and interrater reliability of prehospital SATS triage among a cohort of South African EMS providers

Summary

Introduction

The South African Triage Scale (SATS) is a validated in-hospital triage tool that has been innovatively adopted for use in the prehospital setting by Western Cape Government (WCG) Emergency Medical Services (EMS) in South Africa. The study sought to assess the validity and reliability of SATS when used by WCG EMS prehospital providers for single-patient triage. In a patient experiencing an acute stroke or myocardial infarction, for example, triage performed by emergency medical services (EMS) providers may allow earlier prehospital recognition of the acute condition thereby triggering faster delivery of appropriate pre- and in-hospital care to help minimize morbidity and mortality [1,2,3]. A 2018 systematic review of in-hospital adult emergency care triage tools used in low-and-middle income countries concluded that the South African Triage Scale (SATS) had the highest quality of evidence with sensitivity and specificity of 70–75% and 91–97%, respectively [4]. The final SATS colors used to denote triage acuity and priority, from highest to lowest acuity, are: Red, Orange, Yellow, and Green; Blue is dead) [2, 6, 9, 10]

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