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Table 4 Active TB incidence rates for treatment status, CXR findings, and overseas TB classification by IGRA result

From: Tuberculosis progression rates in U.S. Immigrants following screening with interferon-gamma release assays

Treatment status,a CXR, and TB class by IGRA result n (% of all participants) Incident active TB cases, n (% cases in sub-group) Total follow-up (person-years) Incidence rate per 100,000 person-years (95 % CI)
All participants 1152 (100) 7 (0.60) 7730 91 (43–190)
 IGRA- 639 (55) 2 (0.31) 4139 48 (12–193)
 IGRA+ 513 (45) 5 (0.97) 3591 139 (58–335)
Inadequate or no TB treatment 498 (43) 4 (0.80) 3148 127 (48–339)
 IGRA- 433 (38) 2 (0.46) 2698 74 (19–296)
 IGRA+ 65 (6.0) 2 (3.1) 451 443 (111–1775)
Adequate TB treatment 654 (57) 3 (0.46) 4581 65 (21–203)
 IGRA- 206 (18) 0 1441 0
 IGRA+ 448 (39) 3 (0.67) 3140 96 (31–296)
Normal CXRb 269 (23) 1 (0.37) 1553 64 (9.1–457)
 IGRA- 216 (19) 0 1206 0
 IGRA+ 53 (4.6) 1 (1.9) 347 288 (41–2047)
Abnormal CXR 881 (77) 6 (0.68) 6158 97 (44–217)
 IGRA- 421 (37) 2 (0.48) 2914 69 (17–274)
 IGRA+ 460 (40) 4 (0.87) 3244 123 (46–329)
B1 TB, Pulmonary 561 (49) 5 (0.89) 3630 138 (57–331)
 IGRA- 276 (24) 1 (0.36) 1759 57 (8.0–404)
 IGRA+ 285 (25) 4 (1.4) 1870 214 (80–570)
B2 (LTBI) 588 (51) 2 (0.34) 4084 49 (12–196)
 IGRA- 361 (31) 1 (0.28) 2370 42 (5.9–300)
 IGRA+ 227 (20) 1 (0.44) 1714 58 (8.2–414)
B3 (Contacts) 3 (0.26) 0 16 0
  1. Abbreviations: TB tuberculosis, IGRA interferon-gamma release assay
  2. aTreatment status reflects any TB treatment received up until the time of diagnosis with active TB: either overseas treatment for TB infection or disease prior to U.S. entry, or LTBI treatment received in the U.S. after immigration
  3. b n = 1150 (2 participants missing CXRs)