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Table 4 Sensitivity, specificity and predictive values of Xpert MTB/RIF assay in reference to AFB smear and Bactec-MGIT960 culture in induced sputum (n = 260) vs. gastric aspirate (n = 260) samples

From: Xpert MTB/RIF assay can be used on archived gastric aspirate and induced sputum samples for sensitive diagnosis of paediatric tuberculosis

 

Sensitivity

Specificity

PPV

NPV

LRF of positive test

Diagnostic accuracy

Sensitivity (smear positive)

Sensitivity (smear negative)

Xpert MTB/RIF assay vs Culture

Induced Sputum

35/50 (70.0 %; 56.2–80.9)*

198/210 (94.3 %; 90.3–96.7)**

74.5 % (60.5–84.6)

92.7 % (88.7–95.7)

12.2 % (10.2–14.8)

89.6 % (85.3–92.8)

6/6 (100 %)

29/44 (65.9 %)

Gastric Aspirate

52/77 (67.5 %; 56.5–76.9)*

164/183 (89.6 %; 84.3–93.2)**

73.2 % (61.9–82.1)

87.8 % (81.2–90.9)

6.5 % (5.8–7.3)

83.1 % (78.0–87.1)

16/17 (94.1 %)

36/60 (60.0 %)

AFB vs Culture

Induced Sputum

6/50 (12.0 %; 5.6–23.8)***

210/210 (100 %; 98.2–100)

100 % (60.8–100)

82.7 % (77.5–86.8)

-

83.1 % (78.1–87.1)

NA

NA

Gastric Aspirate

17/77 (22.1 %; 14.3–32.5)

183/183 (100 %; 97.9–100)

100 % (81.6–100)

75.3 % (71.4–81.6)

-

76.9 % (71.4–81.6)

NA

NA

  1. Data n/N (%; 95 % CI) or % (95 % CI), Positive predictive value (PPV), negative predictive value (NPV), Likelihood ratio (LRF), * p = 0.77, ** p = 0.087, *** p = 0.792