Figures
- Fig. 1—
Flow diagram of the study population. QFT: QuantiFERON®-TB Gold in-tube (Cellestis Limited, Carnegie, Australia); TST: tuberculin skin testing; +: positive; -: negative.
Tables
- Table 1—
Associations of demographic, epidemiological and clinical characteristics and therapy with QuantiFERON®-TB Gold in-tube (QFT-GIT)- and tuberculin skin test (TST)-positive results in subjects with rheumatic diseases: univariate analysis
Total QFT-GIT positive p-value# TST positive p-value# Total 393 (100) 52 (13.2) 74 (18.8) Sex 0.03 0.09 Male 137 (34.9) 25 (18.2) 32 (23.4) Female 256 (65.1) 27 (10.5) 42 (16.4) BCG vaccinated 0.1 0.009 Yes 16 (4.1) 0 7 (9.5) No 377 (95.9) 52 (100.0) 67 (90.5) Birth/residence in countries at high prevalence of TB 0.7 0.05 Yes 18 (4.6) 2 (3.8) 7 (9.5) No 375 (95.4) 50 (96.2) 67 (90.5) Age yrs 0.001 0.03 ≤29 45 (11.5) 1 (2.2) 2 (4.4) 30–49 129 (32.8) 12 (9.3) 25 (19.4) 50–69 167 (42.5) 25 (15) 35 (21.0) >70 52 (13.2) 14 (26.9) 12 (23.1) Chest radiograph patterns 0.08 0.009 No lesions of past TB 80 (20.3) 6 (7.5) 14 (17.5) Lesions of past TB 41 (10.5) 9 (22.0) 15 (36.5) Other patterns 272 (69.2) 37 (13.5) 45 (16.5) Close contact to patients with sputum-positive TB 0.02 0.02 Yes 7 (1.8) 3 (5.7) 4 (5.4) No 386 (98.2) 49 (94.3) 70 (94.6) Diagnosis 0.3 0.4 Rheumatoid arthritis 201 (51.1) 27 (13.4) 35 (17.4) Psoriasic arthritis 94 (23.9) 23 (24.5) 16 (17) Ankilosing spondilytis 58 (14.8) 5 (8.6) 11 (19) Other¶ 40 (10.2) 4 (10) 5 (12.5) Therapy+ No therapy in last 3 months 83 (21.1) 13 (25) 22 (29.7) DMARDs 75 (19.1) 12 (23.1) 0.9 19 (25.7) 0.8 DMARDs + steroids 106 (27) 13 (25) 0.5 22 (29.7) 0.3 Steroids 34 (8.7) 2 (3.8) 0.1 1 (1.3) 0.004 TNF-α inhibitors 30 (7.6) 6 (11.5) 0.2 4 (5.4) 0.1 TNF-α inhibitors + DMARDs 25 (6.4) 4 (7.6) 0.9 4 (5.4) 0.2 TNF-α inhibitors + steroids 4 (1) 0 0.3 0 0.2 TNF-α inhibitors + DMARDs + steroids 36 (9.2) 2 (3.8) 0.1 2 (2.7) 0.009 Data are expressed as n (%), unless otherwise stated. BCG: bacillus Calmette–Guérin; TB: tuberculosis; DMARD: disease-modifying antirheumatic drugs; TNF-α: tumour necrosis factor-α. #: by Chi-squared test or Fisher's exact test as appropriate. ¶: includes uveitis, Crohn's disease, juvenile chronic arthritis, undifferentiated spondyloarthropathy (n = 3 for each); Behçet's disease, Still's disease, enteritis, temporal arteritis, scleroderma, seronegative oligoarthritis, seronegative spondyloarthritis, ulcerative colitis (n = 2 for each); systemic lupus erythematosus, systemic sclerosis, erythema nodosum, Wegener's granulomatosis, polymyalgia syndrome, sarcoidosis, reactive arthritis, psoriasis, myopathy of unclear origin, familial mediterranean fever, sacroileitis and seronegative spondyloarthritis with Castleman's disease (n = 1 for each). +: p-values were derived from comparison of the test results in patients with each single regimen and those of untreated patients. QFT-GIT from Cellestis Limited, Carnegie, Australia.
- Table 2—
Risk factors associated with QuantiFERON® in-tube (QFT-GIT) and tuberculin skin test (TST) positivity in subjects with rheumatic diseases: multivariate analysis
QFT-GIT positive TST positive OR (95% CI) p-value OR (95% CI) p-value Male 2.1 (1.1–4.2) 0.01 1.65 (0.9–2.9) 0.08 BCG vaccinated NA NA 3.8 (1.0–13.9) 0.04 Age yrs ≤29 Ref Ref 30–49 2.8 (0.3–23.4) 0.3 8.6 (1.0–69.7) 0.04 50–69 6.8 (0.8–53.0) 0.06 14.7 (1.8–117.2) 0.01 >70 15.9 (1.9–132.0) 0.01 13.2 (1.5–112.7) 0.01 Chest radiograph patterns No lesions of past TB Ref Ref Lesions of past TB 1.3 (0.5–3.2) 0.5 3.0 (1.3–6.8) 0.005 Other patterns 0.4 (0.1–1.2) 0.1 1.6 (0.7–3.4) 0.1 Immunosuppressive therapy including Steroids 0.4 (0.2–0.9) 0.03 0.3 (0.2–0.6) 0.002 DMARD 1.1 (0.5–2.3) 0.7 1.7 (0.9–3.4) 0.09 TNF-α inhibitors 0.9 (0.4–2) 0.8 0.3 (0.1–0.6) 0.004 Close contacts of patients with sputum-positive TB 5.3 (1–28) 0.04 6.5 (1.1–36.9) 0.03 Birth/residence in countries at high prevalence of TB 1.1 (0.2–5.8) 0.8 3.7 (1.1–12.3) 0.03 OR: odds ratio; CI: confidence interval; BCG: bacillus Calmette–Guérin; TB: tuberculosis; DMARD: disease-modifying antirheumatic drugs; TNF-α: tumour necrosis factor-α; NA: not available; Ref: reference. QFT-GIT from Cellestis Limited, Carnegie, Australia.
- Table 3—
Association between number of risk factors for tuberculosis infection and QuantiFERON®-TB Gold in-tube (QFT-GIT) and tuberculin skin test (TST) positivity
Number of risk factors# QFT-GIT positive TST positive p-value¶ OR (95% CI) p-value OR (95% CI) p-value 0 1 1 1 3.30 (1.48–7.39) 0.004 2.57 (1.35–4.90) 0.004 0.730 ≥2 5.71 (2.13–15.31) 0.001 5.35 (2.34–12.20) <0.001 OR: odds ratio; CI: confidence interval. #: aged ≥50 yrs, chest radiograph suggestive of a past tuberculosis (TB), close contact with patients with sputum-positive TB, birth/residence in a country with high incidence of TB; ¶: for the conjoint hypothesis of no difference in the estimates of the two models. QFT-GIT from Cellestis Limited, Carnegie, Australia.
- Table 4—
Estimate of the prevalence of latent tuberculosis using different approaches
Test considered Estimated rate % (95% CI) Only TST positive 18.8 (14.9–22.7) Only QFT-GIT positive 13.2 (9.8–16.5) QFT-GIT and TST positive 9.9 (6.9–12.8) QFT-GIT among TST positive 9.9 (6.9–12.8) At least one positive test 22.1 (18–26.2) CI: confidence interval; TST: tuberculin skin test; QFT-GIT: QuantiFERON®-TB Gold in-tube (Cellestis Limited, Carnegie, Australia).
- Table 5—
Concordance of the interferon-γ release assay (IGRA) and the tuberculin skin test (TST) for the screening of tuberculosis infection in the immunomediated inflammatory disease population
Study Country IGRA kind Subjects n BCG % Indeterminate % κ Concordant results Discordant results TST+/IGRA+ TST-/IGRA- TST-/IGRA+ TST+/IGRA- Cobanoglu 21 Turkey QFT-GIT 68 cases38 controls 100 10.35.3 0.14-0.05 8 (13.1)0 23 (37.7)23 (63.8) 1 (1.6)1 (2.8) 29 (47.5)12 (33.3) Sellam# 22 France ELISPOT¶ 35 cases33 controls 100 0 NA NA NA NA Matulis+ 23 Switzerland QFT-GIT 142 83 6 0.16 10 (7) 60 (44.7) 5 (3.5) 34 (25.4) Pratt 24 UK QFT-GIT 101 78.5 9.9 NA§ NA§ NA§ NA§ Kobashi§ 25 Japan QFT-G 252 60.3 12.6 0.29 30 (13.6) 120 (54.5) 6 (2.8) 64 (29.1) Dinser 26 Germany Flow cytometric assay 97 5.1 0 0.31 6 (6.2) 74 (76.3) 10 (10.3) 7 (7.2) Ponce de Leon 27 Peru QFT-GIT 101 cases93 controls 80.280.6 1.90 0.370.55 21 (20.8)16 (17.2) 50 (49.5)61 (65.6) 24 (23.8)5 (5.4) 6 (5.9)11 (11.8) Vassiloupolos 28 Greece T-SPOT TB 70 40 0 0.38 12 (17.1) 39 (55.7) 4 (5.7) 15 (21.5) Bocchino 29 Italy QFT-GITT SPOT TB 6969 2.82.8 2.85.8 0.570.48 14 (20.9)12 (18.5) 41 (61.2)39 (60) 8 (11.9)9 (13.8) 4 (6)5 (7.7) Greenber 30 USA QFT-G 61 cases42 controls 27.823.3 11.52.4 NA NA NA NA Present data Italy QFT-GIT 398 4.1 1.5 0.55 39 (10) 306 (77.8) 13 (3.3) 35 (8.9) BCG: bacillus Calmette–Guérin; +: positive; -: negative; QFT-GIT: QuantiFERON®-TB Gold in-tube (culture filtrate protein (CFP)-10, early secreted antigenic target (ESAT)-6 and tuberculosis-7; Cellestis Limited, Carnegie, Australia); ELISPOT: enzyme-linked immunospot; QFT-G: QuantiFERON®-TB Gold (CFP-10 and ESAT-6, Carnegie); NA: not available. #: no direct comparison between the two tests. ¶: home-made ELISPOT with antigens CFP-10 and ESAT-6. +: TST analysed retrospectively. The median time between performing the TST and the QFT-GIT assay was 102 days (range 7–184). §: nonhomogeneous population including different underlying diseases (74 subjects had malignant diseases, 72 subjects were undergoing immunosuppressive treatment with steroids and/or tumour necrosis factor-α inhibitors, 52 subjects had diabetes mellitus, 50 subjects had chronic renal failure, four subjects had HIV infection). T-SPOT TB manufactured by Oxford Immunotec, Abingdon, UK.
