The association between factors relevant to M. tuberculosis infection and test reactivity to either the QuantiFeron test or the tuberculin skin test.
| N | QuantiFeron Test | p | N | Tuberculin Skin Test | p | |||
|---|---|---|---|---|---|---|---|---|
| Test Positive, N (%) | RR (95% CI)* | Test Positive, N (%) | RR (95% CI)* | |||||
| Total | 294 | 21 (7) | 241 | 45 (19) | ||||
| Diagnoses | 0.4 | 0.08 | ||||||
| Rheumatoid arthritis | 151 | 13 (9) | 1 | 141 | 28 (20) | 1 | ||
| Sarcoidosis | 50 | 1 (2) | 0.3 (0.01–1.3) | 8 | 1 (13) | 0.7 (0.1–4.9) | ||
| Spondyloarthropathies | 39 | 2 (5) | 0.6 (0.1–2.3) | 39 | 11 (28) | 1.6 (0.9–2.9) | ||
| Other** | 37 | 4 (11) | 1.4 (0.4–3.5) | 35 | 3 (9) | 0.4 (0.1–1.4) | ||
| Unknown*** | 17 | 1 (6) | — | 18 | 2 (11) | — | ||
| Born in a TB-endemic area† | ||||||||
| Yes | 26 | 9 (35) | 7.8 (1.5–18.2) | < 0.0001 | 18 | 6 (33) | 1.7 (0.7–3.1) | 0.2 |
| No | 268 | 12 (5) | 1 | 223 | 39 (17) | 1 | ||
| BCG vaccination | ||||||||
| Yes | 148 | 9 (6) | 0.8 (0.2–3.9) | 0.7 | 140 | 23 (16) | 0.9 (0.4–3.1) | 0.9 |
| No | 45 | 4 (9) | 1 | 42 | 5 (12) | 1 | ||
| Unknown*** | 101 | 8 (8) | — | 59 | 17 (29) | — | ||
| Radiograph indicative of TB | ||||||||
| Yes | 12 | 1 (8) | 1.4 (0.1–5.7) | 0.7 | 11 | 1 (9) | 0.7 (0.04–2.6) | 0.6 |
| No | 282 | 20 (7) | 1 | 230 | 44 (19) | 1 | ||
| Previous TB treatment | ||||||||
| Yes | 7 | 2 (29) | 4.7 (1.6–13.5) | 0.005 | 6 | 2 (33) | 2.7 (0.6–11.5) | 0.5 |
| No | 240 | 16 (7) | 1 | 231 | 42 (18) | 1 | ||
| Unknown*** | 47 | 3 (6) | — | 4 | 1 (25) | |||
| History of TB contact | ||||||||
| Yes | 22 | 1 (5) | 0.3 (0.0–4.6) | 0.6 | 20 | 5 (25) | 1.4 (0.5–2.7) | 0.4 |
| No | 224 | 17 (8) | 1 | 216 | 40 (19) | 1 | ||
| Unknown*** | 48 | 3 (6) | — | 5 | 0 | — | ||
| Visit TB-endemic areas > 3 months | ||||||||
| Yes | 17 | 1 (6) | 1.0 (0.1–8.0) | 0.9 | 17 | 5 (30) | 1.5 (0.6–3.3) | 0.4 |
| No | 202 | 14 (7) | 1 | 206 | 37 (18) | 1 | ||
| Unknown*** | 75 | 6 (8) | — | 18 | 3 (17) | — | ||
| Any LTBI risk factor†† | ||||||||
| Yes | 68 | 12 (18) | 4.7 (2.1–11.0) | 0.0002 | 58 | 16 (28) | 1.5 (0.7–2.9) | 0.3 |
| No | 226 | 9 (4) | 1 | 183 | 29 (16) | 1 | ||
| Corticosteroid treatment | ||||||||
| Yes | 48 | 2 (4) | 0.5 (0.1–1.6) | 0.3 | 38 | 3 (8) | 0.4 (0.1–1.0) | 0.04 |
| No | 246 | 19 (8) | 1 | 203 | 42 (21) | |||
| DMARD treatment | ||||||||
| Yes | 166 | 10 (6) | 0.7 (0.3–1.7) | 0.4 | 76 | 12 (16) | 1.3 (0.7–2.3) | 0.3 |
| No | 128 | 11 (9) | 1 | 165 | 33 (20) | 1 | ||
| CD4 count | ||||||||
| < 500 | 22 | 2 (9) | 1 (0.2–3.2) | 1.0 | 19 | 6 (32) | 1.5 (0.7–3.3) | 0.4 |
| ≥ 500 | 167 | 14 (8) | 1 | 167 | 31 (19) | 1 | ||
| Unknown*** | 105 | 5 (5) | — | 55 | 8 (15) | — | ||
↵* The regression excluding the unknown numbers in the analysis. RR is adjusted for age and sex.
↵** Including psoriatic arthritis, Morbus Still, polymyositis, HLA-B27 arthritis, polyarthritis.
↵*** Missing questionnaire data were categorized as unknown.
↵† TB-endemic areas defined by WHO as countries with a TB incidence > 25/100,000/yr.
↵†† Any LTBI risk factor is categorized as present, when at least one of the following risk factors is present: birth in TB-endemic area, visit to TB-endemic area > 3 months, prior TB contact, radiograph indicative of TB or prior TB treatment.