Associations between factors relevant to M. tuberculosis infection and QuantiFeron and tuberculin skin test concordance.
| Total No. of Pair-wise Analyses, N | Concordant Test Results*, N (%) | Discordant Test Results*, N (%) | p** | |
|---|---|---|---|---|
| BCG vaccination | ||||
| No | 40 | 34 (85) | 6 (15) | 0.6 |
| Yes | 136 | 110 (81) | 26 (19) | |
| Unknown*** | 58 | — | — | |
| Corticosteroid treatment | ||||
| No | 197 | 131 (76) | 41 (24) | 0.07 |
| Yes | 37 | 34 (92) | 3 (8) | |
| DMARD treatment | ||||
| No | 74 | 60 (81) | 14 (19) | 1.0 |
| Yes | 160 | 129 (81) | 31 (19) | |
| CD4 count | ||||
| ≥ 500 | 163 | 130 (80) | 33 (20) | 1.0 |
| < 500 | 19 | 15 (79) | 4 (21) | |
| Unknown*** | 52 | — | — | |
| Visit TB-endemic area > 3 months | ||||
| Yes | 16 | 10 (63) | 6 (38) | 0.09 |
| No | 201 | 166 (83) | 35 (19) | |
| Unknown*** | 17 | — | — | |
| History of TB contact | ||||
| Yes | 20 | 13 (76) | 4 (24) | 1.0 |
| No | 209 | 169 (81) | 40 (19) | |
| Unknown*** | 5 | — | — | |
| Previous TB treatment | ||||
| Yes | 6 | 5 (83) | 1 (17) | 1.0 |
| No | 224 | 182 (81) | 42 (19) | |
| Unknown*** | 4 | — | — | |
| Radiograph indicative of TB | ||||
| Yes | 11 | 11 (100) | 0 (0) | 0.1 |
| No | 223 | 178 (80) | 45 (20) | |
| Born in TB-endemic area | ||||
| Yes | 18 | 13 (72) | 5 (28) | 0.4 |
| No | 216 | 176 (81) | 40 (19) | |
| Any LTBI risk factor† | ||||
| Yes | 57 | 43 (75) | 14 (25) | 0.3 |
| No | 177 | 146 (82) | 31 (18) | |
| Diagnoses | ||||
| Rheumatoid arthritis | 139 | 112 (81) | 27 (19) | 0.1 |
| Sarcoidosis | 8 | 8 (100) | 0 (0) | |
| Spondyloarthropathies | 38 | 27 (71) | 11 (29) | |
| Other† | 35 | 31 (89) | 4 (11) | |
| Unknown*** | 14 | — | — | |
↵* Number of cases where both TST and QuantiFeron test results are either positive or negative or where the 2 test results differ (discordant).
↵** Chi-square test.
↵*** Missing questionnaire data were categorized as unknown.
↵† 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.
†† Including psoriatic arthritis, M. Still, polymyositis, HLA-B27 arthritis, polyarthritis.