PCR colorimetric dot-blot assay and clinical pretest probability for diagnosis of Pulmonary Tuberculosis in Smear-Negative patients

Table 2 Performance of Culture, PCR dot-blot and Clinical suspicion tests, individually and associated, in 151 smear negative PTB suspects

Table 2A. Laboratory results and Performance of methods
		All Group^a N = 151				Non previously TB treated Group^b N = 98
		TB N = 43		Non-TB N = 108		TB N = 36		Non-TB N = 62
Culture	Positive	30		0		27		0
	Negative	13		108		9		62
		SE	SP	PPV	NPV	SE	SP	PPV	NPV
		70%	100%	100	89	75%	100%	100	87
PCR dot-blot	Positive	28		18		25		9
	Negative	15		90		11		53
		SE	SP	PPV	NPV	SE	SP	PPV	NPV
		65%	83%	61	86	69%	85%	73	83
High PP	Positive	31		15		26		4
	Negative	12		93		10		58
		SE	SP	PPV	NPV	SE	SP	PPV	NPV
		72%	86%	67	88	72%	93%	87	85
Intermediate PP	Positive	6		19		6		6
	Negative	37		89		30		56
		SE	SP	PPV	NPV	SE	SP	PPV	NPV
		14%	82%	24	71	17%	90%	50	65
Low PP	Positive	6		74		4		52
	Negative	37		34		32		10
		SE	SP	PPV	NPV	SE	SP	PPV	NPV
		14%	31%	7.5	48	11%	16%	7.1	24
Table 2B. Performance of methods used in parallel
Performance of PCR dot-blot in parallel with High Clinical Suspicion		SE	SP	PPV	NPV	SE	SP	PPV	NPV
		90%	71%	75	88	91%	79%	81	90
Performance of PCR dot-blot in parallel with Intermediate Clinical Suspicion		SE	SP	PPV	NPV	SE	SP	PPV	NPV
		70%	68%	68	70	74%	77%	75	76
Performance of PCR dot-blot in parallel with Low Clinical Suspicion		SE	SP	PPV	NPV	SE	SP	PPV	NPV
		26%	25%	47	47	26%	14%	45	34

SE: Sensitivity, SP: Specificity, PPV: Positive Predictive Value, NPV: Negative Predictive Value, PP: pretest probability (clinical suspicion).
a: All group.
b: Non previously TB treated group patients

ISSN: 1471-2458