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Table 3 Comparative performance of SSM versus LAM; and the combination of SSM and LAM versus SSM alone using composite reference standard

From: Comparative performance characteristics of the urine lipoarabinomannan strip test and sputum smear microscopy in hospitalized HIV-infected patients with suspected tuberculosis in Harare, Zimbabwe

 

SSM versus LAM

Combined SSM and LAM versus SSM alone

N = 457

SSM only

LAM only

p-value

SSM only

LAM only

SSM plus LAM

p-value

Sensitivity

29.4 %

49.2 %

<0.001

29.4 %*

49.2 %

57.4 % *

<0.001

(95 % CI)

(23.2-36.3)

(42.1-56.4)

 

(23.2-36.3)

(42.1-56.4)

(50.1-64.4)

 

n + ve/total

58/197

97/197

 

58/197

97/197

113/197

 

Specificity

98.8 %

98.1 %

0.476

98.8 %

98.1 %

98.1 %

>0.05

(95 % CI)

(96.7-99.8)

(95.6-99.4)

 

(96.7-99.8)

(95.6-99.4)

(95.6-99.4)

 

n -ve/total

257/260

255/260

 

255/260

255/260

255/260

 

PPV

95.1 %

95.1 %

0.996

95.1 %

95.1 %

95.8 %

>0.05

(95 % CI)

(86.3-99.0)

(88.9-98.4)

 

(86.3-99.0)

(88.9–98.4)

(90.4-98.6)

 

NPV

64.9 %

71.8 %

0.042

64.9 %*

71.8 %

75.2 %*

<0.001

(95 % CI)

(60.0-69.6)

(66.8–76.5)

 

(60.0-69.6)

(66.8-76.5)

(70.3-79.7)

 
  1. SSM sputum smear microscopy, LAM urine Lipoarabinomannan strip test, n + ve number positive, n –ve number negative
  2. P-value indicate significant differences between patient groups (marked with * and number to indicate comparison group) * - Significantly different (p ≤ 0.05)