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Table 2 Performance parameters of ZN, Magnetic bead FM and concentrated FM compared with culture

From: Feasibility of magnetic bead technology for concentration of mycobacteria in sputum prior to fluorescence microscopy

  Direct ZN Magnetic bead-FM Concentrated FM Direct FM*
Sensitivity, %
(95% CI)
51.4%
(41.5 - 61.2)
65.4%
(55.6 - 74.4)
74.8%
(65.4 - 82.7)
58.9%
(49.0 - 68.3)
Specificity, %
(95% CI)
98.9%
(95.9 - 99.9)
88.6%
(82.9 - 92.9)
94.3%
(89.7 - 97.2)
99.4%
(96.9 - 100.0)
Overall accuracy, %
(95% CI)
80.9%
(75.8 - 85.3)
79.8%
(74.6 - 84.3)
86.9%
(82.4 - 90.6)
84.0%
(79.2 - 88.1)
PPV, %
(95% CI)
96.5%
(87.9 - 99.6)
77.8%
(67.8 - 85.9)
88.9%
(80.5 - 94.5)
98.4%
(91.6 - 100.0)
NPV, %
(95% CI)
76.9%
(70.8 - 82.2)
80.7%
(74.4 - 86.1)
85.9%
(80.2 - 90.5)
78.9%
(73.9 - 84.9)
  1. * Direct FM was performed in the routine microbiology laboratory, Mulago Hospital
  2. CI, confidence interval
  3. PPV, positive predictive value
  4. NPV, negative predictive value
  5. ZN, Ziehl-Neelsen
  6. FM, fluorescence microscopy