Table 2.

Clinical performance metrics for the model in the external validation data set for various score cutoffs and COVID-19 pretest prevalence^a.

Score cutoff	Sensitivity	Specificity	Likelihood ratiob	Prevalence of 1%		Prevalence of 10%		Prevalence of 20%
				NPVc, %	Yieldd, %	NPV, %	Yield, %	NPV, %	Yield, %
1	95.9	41.7	0.099	99.9	41.3	98.9	38.0	97.6	34.2
2	92.6	60.0	0.124	99.9	59.4	98.6	54.7	97.0	49.5
5	85.5	78.5	0.185	99.8	77.8	98.0	72.1	95.6	65.7
10	79.4	87.6	0.235	99.8	86.9	97.4	80.9	94.4	74.2

^aThe maximum score was 100; a higher score indicates higher model prediction of COVID-19 positivity.

^bThe likelihood ratio uses the equation for negative tests.

^cNPV: negative predictive value.

^dYield refers to diagnostic yield, which is the percentage of patients that can be ruled out (ie, those with a score below the cutoff).