Background
Methods
Study population
TB classification Status | Description |
---|---|
No TB classification | No evidence of TB infection or disease |
A | Smear or culturea positive pulmonary TB. Typically requires treatment prior to U.S. entry. |
B1-Pulmonary | 1. Suspected active pulmonary TB based on clinical findings but with negative sputum smears and culturesa
|
2. History of pulmonary TB, treatment complete | |
B1-Extrapulmonary | Extrapulmonary TB |
B2 | TST ≥ 10 mm or positive IGRA but otherwise negative TB evaluation (LTBI) |
B3 | Recent close contact with a known active TB case and TST/IGRA negative |
Study outcome
Statistical analysis
Results
Baseline demographic and clinical characteristics
Characteristic | All subjects | IGRA-negative | IGRA-positive |
p value |
---|---|---|---|---|
n (%)a
| n (%) | n (%) | ||
All | 1152 (100) | 639 (55) | 513 (45) | |
Median age, years (IQR) | 54 (39–64) | 52 (21–64) | 55 (45–65) | |
Mean age, years (SD) | 49 (20) | 45 (23) | 53 (15) | <0.0001 |
Age by category, years, n (%) |
n = 1152 |
n = 639 |
n = 513 | <0.0001 |
0–4 | 18 (1.6) | 17 (2.7) | 1 (0.2) | |
5–12 | 87 (7.6) | 81 (13) | 6 (1.2) | |
13–20 | 74 (6.4) | 62 (9.7) | 12 (2.3) | |
≥ 21 | 973 (84) | 479 (75) | 494 (96) | |
Gender |
n = 1152 |
n = 639 |
n = 513 | 0.141 |
Male | 645 (56) | 345 (54) | 300 (58) | |
Female | 507 (44) | 294 (46) | 213 (42) | |
Country of origin |
n = 1150 |
n = 638 |
n = 512 | 0.001 |
China | 586 (51) | 302 (47) | 284 (55) | |
Philippines | 386 (34) | 245 (38) | 141 (28) | |
Vietnam | 94 (8.2) | 42 (6.6) | 52 (10) | |
Burma | 18 (1.6) | 11 (1.7) | 7 (1.4) | |
Other | 66 (5.7) | 38 (6.0) | 28 (5.4) | |
HIV status |
n = 799 |
n = 404 |
n = 395 | <0.0001 |
HIV- | 797 (99.8) | 402 (99.5) | 395 (100) | |
HIV+ | 2 (0.25) | 2 (0.5) | 0 | |
Diabetes |
n = 1152 |
n = 639 |
n = 513 | 0.09 |
No | 1090 (95) | 611 (96) | 479 (93) | |
Yes | 62 (5.4) | 28 (4.4) | 34 (6.6) | |
Smoking status |
n = 1152 |
n = 639 |
n = 513 | <0.0001 |
Never | 803 (70) | 476 (74) | 327 (64) | |
Current or Former | 349 (30) | 163 (26) | 186 (36) | |
TB Classification at immigration |
n = 1152 |
n = 639 |
n = 513 | 0.0001 |
B1-Pulmonary (TB suspect or prior TB) | 561 (49) | 276 (43) | 285 (56) | |
B2 (LTBI) | 588 (51) | 361 (56) | 227 (44) | |
B3 (Contact) | 3 (0.26) | 2 (0.31) | 1 (0.19) | |
BCG |
n = 490 |
n = 309 |
n = 181 | 0.004 |
No evidence of BCG vaccination | 114 (23) | 59 (19) | 55 (30) | |
Evidence of BCG vaccination | 376 (77) | 250 (81) | 126 (70) | |
Treatment statusb
|
n = 1152 |
n = 639 |
n = 513 | <0.0001 |
Inadequate or no TB treatment | 498 (43) | 433 (68) | 65 (13) | |
Overseas TB treatment prior to immigration | 324 (28) | 136 (21) | 188 (37) | |
LTBI treatment in U.S. after immigration | 330 (29) | 70 (11) | 260 (51) | |
TST Result |
n = 298 |
n = 230 |
n = 68 | 0.5 |
Negative | 70 (23) | 56 (24) | 14 (21) | |
Positive | 228 (77) | 174 (76) | 54 (79) | |
Immigration CXR Result |
n = 1150 |
n = 637 |
n = 513 | <0.0001 |
Normal | 269 (23) | 216 (34) | 53 (10) | |
Abnormal | 881(77) | 421 (66) | 460 (90) | |
Prevalent TB cases at enrollment | ||||
Total | 81/1233 (6.6) | 27/666 (4.1) | 54/567 (9.5) | 0.0001 |
Microbiologically confirmed | 42/1233 (3.4) | 8/666 (1.2) | 34/567 (6.0) | <0.0001 |
Incident active TB cases
Case | IGRA | Ag-Nil, Mitogen (IU/ml) | CXR findings | HIV | Diabetes | Smoker | TB Class | Treatment statusa
| TB confirmation |
---|---|---|---|---|---|---|---|---|---|
1 | Neg | 0.38–0.11, 20 | Pleural thickening, RUL | Neg | No | No | B1 | None | Lung biopsy pathology |
2 | Pos | 0.93–0.12, 2.0 | Fibronodular changes, BUL & LLL | Unk | No | No | B2 | None | sputum culture |
3 | Neg | 0.29–0.11, 25 | Fibrotic changes, LUL | Neg | No | No | B2 | Incomplete tx prior to immigrationb
| sputum culture |
4 | Pos | 2.4–0.12, 25 | Fibronodular changes, RUL | Neg | No | No | B1 | LTBI tx at enrollment | sputum culture |
5 | Pos | 9.7–0.70, 24 | Normal | Neg | No | No | B1 | LTBI tx at enrollment | sputum culture |
6 | Pos | 3.1–0.12, 8.9 | Nodular infiltrate, LUL | Neg | No | No | B1 | LTBI tx at enrollment | sputum culture |
7 | Pos | 1.1–0.16, 6.9 | Fibrotic changes, LUL; Effusion, L | Neg | No | No | B1 | Incomplete LTBI tx at enrollmentc
| sputum culture |
Incidence rates for active TB disease during follow-up
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 |