Table 4. Simulation of positive and negative predictive values of Ziehl-Neelsen staining, culture, and polymerase chain reaction dot-blot assays, according to different tuberculosis prevalence rates.

Simulated prevalence rates	Subjects with HIV N=74		Subjects without HIV N=203
	TB N=40	TB N=34	TB N=88	TB N=115
	PPV	NPV	PPV	NPV
5%
ZN / cuture	100	99	83	100
ZN / PCR dot-blot	23	99	23	100
	PPV	NPV	PPV	NPV
10%
ZN / cuture	100	99	91	99
ZN / PCR dot-blot	38	98	39	99
	PPV	NPV	PPV	NPV
20%
ZN / cuture	100	97	96	99
ZN / PCR dot-blot	58	98	59	98
	PPV	NPV	PPV	NPV
30%
ZN / cuture	100	95	98	98
ZN / PCR dot-blot	71	93	71	96
	PPV	NPV	PPV	NPV
40%
ZN / cuture	100	93	98	97
ZN / PCR dot-blot	79	89	79	94
	PPV	NPV	PPV	NPV
46%*
ZN / cuture	99	88	98	96
ZN / PCR dot-blot	87	82	83	93

PPV, positive predictive value; NPV, negative predictive value.

^*the present study.