Factors associated with positive QTF-Gold IT, positive T-Spot.TB and positive TST results in bivariate and multivariate analysis
| Bivariate analysis | Multivariate analysis | |||||
|---|---|---|---|---|---|---|
| Positive QTF-Gold IT result (n=39) | Negative or indeterminate QTF-Gold IT result (n=353) | p Value | OR | 95% CI | p Value | |
| Age, median (IQR)/(OR per 10 years) | 53 (43–64) | 44 (33–44) | 0.0006 | 1.42 | 1.09 to 1.85 | 0.0081 |
| RA and SpA (vs CD) | 32 (82.1) | 269 (76.2) | 0.4118 | |||
| Birth in endemic TB zone | 12 (30.8) | 46 (13.1) | 0.0032 | 2.97 | 1.33 to 6.66 | 0.0081 |
| Corticosteroids or immunosuppressors | 26 (66.7) | 2 (58.9) | 0.3495 | |||
| Corticosteroids alone | 19 (48.7) | 121 (34.3) | 0.0741 | |||
| BCG vaccination | 0.0005 | 0.0357 | ||||
| No | 6 (15.4) | 10 (2.8) | 1 | |||
| Yes | 20 (51.3) | 237 (67.1) | 0.23 | 0.07 to 0.73 | ||
| Unknown | 13 (33.3) | 106 (30.0) | 0.23 | 0.07 to 0.77 | ||
| LTBI defined by questioning alone* or chest x-ray† | 12 (30.8) | 45 (12.7) | 0.0024 | 2.30 | 1.04 to 5.11 | 0.0407 |
| Positive T-SPOT.TB result (n=59) | Negative or indeterminate T-SPOT.TB result (n=333) | p Value | OR | 95% CI | p Value | |
| Age, median (IQR)/(OR per 10 years) | 51 (39–60) | 44 (33–54) | 0.0025 | 1.27 | 1.03 to 1.57 | 0.0232 |
| RA and SpA (vs CD) | 53 (89.8) | 248 (74.5) | 0.0100 | 2.69 | 1.08 to 6.71 | 0.0342 |
| Birth in endemic TB zone | 17 (28.8) | 41 (12.3) | 0.0010 | 3.11 | 1.59 to 6.10 | 0.0009 |
| Corticosteroids or immunosuppressors | 36 (61.0) | 198 (59.5) | 0.8221 | |||
| Corticosteroids alone | 23 (39.0) | 117 (35.1) | 0.5697 | |||
| BCG vaccination | 0.1805 | |||||
| No | 5 (8.5) | 11 (3.3) | ||||
| Yes | 37 (62.7) | 220 (66.1) | ||||
| Unknown | 17 (28.8) | 102 (30.6) | ||||
| LTBI defined by questioning alone* or chest x-ray† | 14 (23.7) | 43 (12.9) | 0.0298 | |||
| Positive TST result (n=138) | Negative TST result (n=254) | p Value | OR | 95% CI | p Value | |
| Age, median (IQR)/(OR per 10 years) | 44 (36–51) | 45 (33–58) | 0.1619 | 0.80 | 0.68 to 0.94 | 0.0059 |
| RA and SpA (vs CD) | 120 (87.0) | 181 (46.2) | 0.0004 | 3.76 | 2.04 to 6.91 | <0.0001 |
| Birth in endemic TB zone | 28 (20.3) | 30 (11.9) | 0.0250 | 2.15 | 1.19 to 3.88 | 0.0108 |
| Corticosteroids or immunosuppressors | 73 (52.9) | 161 (63.4) | 0.0432 | |||
| Corticosteroids alone | 41 (29.7) | 99 (39.0) | 0.0674 | |||
| BCG vaccination | 0.2846 | |||||
| No | 6 (4.3) | 10 (3.9) | ||||
| Yes | 97 (70.3) | 160 (63.0) | ||||
| Unknown | 35 (25.4) | 84 (33.1) | ||||
| LTBI defined by questioning alone* or chest x-ray† | 18 (13.0) | 39 (15.4) | 0.5353 | |||
Data are number (%) unless otherwise specified.
↵* TB primary infection, close contact with TB patient, TB with no treatment, anti-TB treatment initiated before 1970 or less than 2 months with the combination rifampicin-pyrazinamide treatment.
↵† Nodules >1 cm.
BCG, bacillus of Calmette and Guerin; LTBI, latent tuberculosis infection; QTF-Gold IT, QuantiFERON TB Gold in tube; RA, rheumatoid arthritis; SpA, spondylarthropathies; TB, tuberculosis; TST, tuberculin skin test.