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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)