Sensitivity of direct versus concentrated sputum smear microscopy in HIV-infected patients suspected of having pulmonary tuberculosis

Table 2 Sensitivity and Specificity of Concentrated and Direct Smear, By Reference Outcome

Concentrated Smear Result	Direct Smear Result		Total
Gold Standard: Sputum Culture
A. Sensitivity
	Positive	Negative
Positive	67 (39%)	22 (13%)	89 (52%)
Negative	20 (12%)	61 (36%)	81 (48%)
Total	87 (51%)	83 (49%)	170 (100%)
Sensitivity of Direct Smear = 0.51 (0.43–0.59)
Sensitivity of Concentrated Smear = 0.52 (0.44–0.61)
Sensitivity of Direct + Concentrated Smear = 0.64 (0.56–0.72)^{a, b}
B. Specificity
	Positive	Negative
Positive	0 (0%)	12 (11%)	12 (11%)
Negative	1 (1%)	96 (88%)	97 (89%)
Total	1 (1%)	108 (99%)	109 (100%)
Specificity of Direct Smear = 0.99 (0.94–1.0)^a
Specificity of Concentrated Smear = 0.89 (0.81–0.95)^b
Specificity of Direct + Concentrated Smear = 0.88 (0.80–0.94)^b
Gold Standard: Sputum Culture + Clinical Criteria
A. Sensitivity
	Positive	Negative
Positive	67 (34%)	27 (14%)	94 (48%)
Negative	20 (10%)	82 (42%)	102 (52%)
Total	87 (44%)	109 (56%)	196 (100%)
Sensitivity of Direct Smear = 0.44 (0.36–0.52)
Sensitivity of Concentrated Smear = 0.48 (0.40–0.56)
Sensitivity of Direct + Concentrated Smear = 0.58 (0.50–0.66)^{a, b}
B. Specificity
	Positive	Negative
Positive	0 (0%)	7 (8%)	7 (8%)
Negative	1 (1%)	75 (90%)	76 (92%)
Total	1 (1%)	82 (99%)	83 (100%)
Specificity of Direct Smear = 0.99 (0.93–1.0)
Specificity of Concentrated Smear = 0.92 (0.83–0.97)
Specificity of Direct + Concentrated Smear = 0.90 (0.81–0.96)^b

ISSN: 1471-2334