Test		Sensitivity (%)*	Specificity (%)	Positive LR	Negative LR	Post-test positive (%)	Post-test negative (%)
Patients with clinically suspected IM; reference standard is positive heterophile antibody10
	≥ 10% atypical lymphocytes	75	92	9.4	0.27	51	3
	≥ 20% atypical lymphocytes	56	98	28	0.44	76	5
	≥ 40% atypical lymphocytes	25	100	50	0.75	100	8
	≥ 50% lymphocytes	66	84	4.1	0.40	31	4
	≥ 50% lymphocytes and ≥ 10% atypical lymphocytes	61	95	12	0.41	58	4
Patients over age 16 with sore throat; reference standard is positive heterophile antibody6
	≥ 50% lymphocytes and ≥ 10% atypical lymphocytes	27	100	54	0.73
Patients with suspected IM; reference standard is positive heterophile antibody and an EBV-VCA antibody pattern compatible with recent infections15–17
	Heterophile antibody–latex agglutination*	87 (range, 79 to 95)	91 (range, 82 to 99)	9.7	0.14	52	2
	Heterophile antibody–solid-phase immunoassay*	83 (range, 71 to 95)	97 (range, 94 to 99)	28	0.18	75	2
	Antibody to VCA or EBNA*	97 (range, 95 to 99)	94 (range, 89 to 99)	16	0.03	64	0.5