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Table 3 The sensitivity and specificity of induration and erythema after EC skin test

From: Induration or erythema diameter not less than 5 mm as results of recombinant fusion protein ESAT6-CFP10 skin test for detecting M. tuberculosis infection

  24 h 48 h 72 h
≥5 mm, N <5 mm, N ≥5 mm, N <5 mm, N ≥5 mm, N <5 mm, N
In TB patients
 Induration diameter 536 207 626 117 620 120
 Erythema diameter 634 109 675 68 674 66
 χ2 38.60 14.82 17.93
P <0.01 <0.01 <0.01
In bacteriologically positive TB patients
 Induration diameter 303 91 341 53 332 62
 Erythema diameter 351 43 369 25 368 26
 χ2 20.72 11.16 16.58
P <0.01 <0.01 <0.01
In bacteriologically nagative TB patients
 Induration diameter 188 94 227 55 231 48
 Erythema diameter 227 55 244 38 244 35
 χ2 13.87 3.72 2.39
P <0.01 0.05 0.12
In extrapulmonary TB patients
 Induration diameter 46 21 58 9 57 10
 Erythema diameter 56 11 62 5 62 5
 χ2 4.11 1.28 1.88
P 0.04 0.26 0.17
In healthy volunteers
 Induration diameter 38 1476 134 1380
 Erythema diameter 70 1444 154 1360
 χ2 9.83 1.54   
P <0.01 0.22   
In BCG vaccination volunteers
 Induration diameter 20 295 16 299
 Erythema diameter 29 286 22 293
 χ2 1.79 1.01   
P 0.18 0.32