A registry-based observational study comparing emergency calls assessed by emergency medical dispatchers with and without support by registered nurses

Table 3 Definition of accuracy: Sensitivity, specificity and predictive values for each RETTS priority

		Ambulance priority level (RETTS: Red/Orange* or Yellow or Green)
		Positive	Negative
Dispatched priority level (Swedish Index: Priority 1 or Priority 2 or Priority 3)	Positive	a	b	Positive Predictive Value PPV = a/(a + b)
	Negative	c	d	Negative Predictive Value NPV = d/(c + d)
		Sensitivity = a/(a + c)	Specificity = d/(b + d)

Accuracy was defined as the sensitivity, specificity and predictive values for each of the ambulance priorities (RETTS Red/Orange or Yellow or Green) compared to the corresponding dispatch priorities (Swedish Index Priority 1 or Priority 2 or Priority 3)
Swedish Index, The Swedish Index to Emergency Medical Assistance; RETTS, The Rapid Emergency Triage and Treatment System
*The Swedish Index and RETTS have unequal numbers of priority levels. The two highest priorities in RETTS were therefore merged into one single priority (Red/Orange), defined as that corresponding to the highest priority in the Swedish Index (Priority 1) to allow for comparisons

ISSN: 1757-7241