Table 3.

Comparison of Performance of CD4 Failure Criteria^a to Various Definitions of Virologic Failure

	Failure
Viral load failure definition	Immunologic and virologic	Immunologic only	Virologic only	None	Sensitivity%	Specificity%	PPV%	NPV%
Confirmed VL >5000 copies/mL (WHO-defined viral failure)	880	2242	449	6119	66.2	73.2	28.2	93.2
Confirmed VL >1000 copies/mL (protocol-defined viral failure)	1225	1897	872	5696	58.4	75.0	39.2	86.7
Confirmed VL >400 copies/mL	1440	1682	1301	5267	52.6	75.9	46.1	80.2

Abbreviations: NPV, negative predictive value; PPV, positive predictive value; VL, viral load; WHO, World Health Organization.

^aImmunologic failure defined in this table as meeting any of the 3 WHO CD4 failure definitions (unconfirmed by a second CD4 value).