Table 5. Incidence and relative risks for active TB in HIV-infected individuals with positive TST, T-SPOT.TB and dual positive results, compared with individuals with negative results.
| Total | Cases | Incidence, cases per 100PY (95% CI) | RR*(95% CI) | P value | |
| All patients | 822 | 4 | 0.17 (0.004–0.33) | ||
| Individuals without IPT | |||||
| TST | |||||
| TST negative | 682 | 0 | - | 1 | |
| TST positive | 140 | 4 | 1.02(0.03–2.02) | 40.6(2.1–767.9) | 0.014 |
| T-SPOT.TB | |||||
| negative | 737 | 0 | - | 1 | |
| positive | 85 | 4 | 1.72(0.05–3.39) | 73.9(3.9–1397.7) | 0.004 |
| Dual Positive of TST and T-SPOT.TB | |||||
| Negative/single positive | 790 | 0 | - | 1 | |
| Dual positive | 32 | 4 | 4.93(0.22–9.63) | 226.5(12.0–4284) | 0.0003 |
Definition of abbreviations: BCG = Bacille Calmette-Guérin; CI = confidence interval; IPT = isoniazid preventive therapy; PY = person-year; TST = tuberculin skin test. RR = relative risk.
*Relative risk was calculated by Poisson regression method and the cell with “zero case” was assigned to 0.5 for calculation.
Individuals with IPT were excluded.