Table 4.

Performance of stacked ensemble algorithms using the first (high sensitivity) and second (high specificity) operating points. The baseline models were the decision by the EMS clinician whether to convey the patient to hospital or not and the recommendation arising from the use of the PRIEST clinical severity score [11].

	Model	Sensitivity	Specificity	npv	ppv	GM	AUC
Baseline	EMS clinician	0.84	0.39	0.92	0.23	0.57	NA
	PRIEST score	0.97	0.41	0.98	0.26	0.63	0.83 ± 0.01
(a) High sensitivity	SVM,XGB	0.98	0.42	0.99	0.26	0.64	0.86 ± 0.01
	ANN,SVM	0.96	0.73	0.99	0.45	0.84	0.95 ± 0.01
	ANN,XGB	0.95	0.73	0.98	0.43	0.83	0.95 ± 0.01
	ANN,SVM,XGB	0.99	0.47	0.99	0.29	0.68	0.95 ± 0.01
(b) High specificity	SVM,XGB	0.93	0.60	0.98	0.33	0.74	0.86 ± 0.01
	ANN,SVM	0.92	0.83	0.98	0.57	0.88	0.95 ± 0.01
	ANN,XGB	0.90	0.83	0.98	0.53	0.86	0.95 ± 0.01
	ANN,SVM,XGB	0.90	0.83	0.98	0.53	0.86	0.95 ± 0.01