Table 2.

Natural frequency estimates based on the summary sensitivity and specificity and median prevalence of strep A infection from the systematic review of rapid tests for diagnosing group A streptococcus in children with sore throats

	Disease present	Disease absent	Total
Test positive	300 × 0.857 = 257	700 − (700 × 0.954) = 32	TP + FP = 289
Test negative	300 − (300 × 0.857) = 43	700 × 0.954 = 668	FN + TN = 711
	1000 × 0.3 = 300	1000 − 300 = 700	1000