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Table 2 Sensitivity and specificity of smear microscopy and chest-x-ray for M.tb and NTM by HIV status

From: Cost-effectiveness of point-of-care digital chest-x-ray in HIV patients with pulmonary mycobacterial infections in Nigeria

   HIV positive (n = 219) HIV negative (n = 733)
   M.tb (n = 69) NTM (n = 26) M.tb (n = 185) NTM (n = 39)
% (95% CI) % (95% CI) % (95% CI) % (95% CI)
Sputum smear test for all TB suspects Sensitivity 49.3 [42.7-55.9] 7.7 [3.4-12.0] 69.7 [66.4-73.0] 10.3 [7.8-12.8]
Specificity 81.3 [78.6-83.7] 78.7 [75.9-81.2] 90.9 [88.6-92.7] 78.6 [75.9-81.2]
PPV 17.1 [12.5-22.9] 1.0 [0.3-3.6] 64.8 [58.0-71.1] 2.0 [0.8-5.1]
NPV 95.4 [93.6-96.4] 96.8 [95.3-97.9] 92.6 [90.5-94.2] 95.4 [93.6-96.6]
Chest-x-ray for smear-negative TB suspects Net sensitivity 78.3 [72.3-84.3] 42.3 [34.2-50.4] 90.3 [87.9-92.7] 48.7 [44.4-53.0]
Net specificity 65.9 [62.7-68.7] 62.9 [59.7-65.9] 75.5 [72.3-78.4] 63.2 [60.0-66.3]
Net PPV 15.2 [14-16.3] 3.1 [2.6-3.7] 47.0 [45.4-48.6] 5.4 [4.7-6.1]
Net NPV 97.5 [96.1-98.6] 97.5 [97.1-97.8] 97.0 [96.6-97.4] 96.6 [96.1-97.0]
Incremental yield 29.0 [22.4-35.7] 34.6 [26.8-42.4] 20.6 [17.3-23.9] 38.4 [34.2-42.6]
  1. M.tb Mycobacterium tuberculosis complex, NTM Non-tuberculous Mycobacteria, PPV Positive predictive value, NPV Negative predictive value, 95% CI 95% confidence interval.