Table 2.

Performance of Immunologic Failure Criteria^* to Predict Various Definitions of Virologic Failure among Clients Receiving First-line ART

	Immunologic/Virologic failure status
	Immunologic only	Immunologic & Virologic	Virologic only	None	Sens	Spec	PPV	NPV	Accuracy+	VL Fail Rate
Virologic failure criteria
At least 1 VL > 10,000 copies/ml	107	18	62	946	0.23	0.90	0.14	0.94	0.85	0.07
(with F/U confirmatory CD4)#	53	11	69	1000	0.14	0.95	0.17	0.94	0.89	0.07
At least 2 VL > 5,000 copies/ml	115	10	26	982	0.28	0.90	0.08	0.97	0.88	0.03
(with F/U confirmatory CD4)#	58	6	30	1039	0.17	0.95	0.09	0.97	0.92	0.03
At least 2 VL > 400 copies/ml	99	26	86	922	0.23	0.90	0.21	0.91	0.84	0.10
(with F/U confirmatory CD4)#	54	10	102	967	0.09	0.95	0.16	0.90	0.86	0.10

^*Includes: 1) persistent CD4 < 100cells/mm³ (i.e. CD4 < 100 at consecutive measurements from M6, but not more than 12 months apart); 2) any drop below baseline CD4 count from M6; 3) any single drop > 50% CD4 max from M6. For criteria 2 and 3, CD4 must also be < 200.

⁺Accuracy = (true positive results + true negative results) / total subjects

^#Immunologic failure is defined as any of the above criteria that have been confirmed at a consecutive measurement within 12 months.