Variable | Baseline | Range | Source |
---|---|---|---|
Probabilities | Â | Â | Â |
Prevalence of LTBI | 0.30 | 0.1-0.4 | |
TST return rate | 0.90 | 0.65-0.95 | |
T-SPOT.TB sensitivity | 0.95 | 0.83-0.97 | |
T-SPOT.TB specificity | 1.00 | 0.92-0.99 | |
T-SPOT.TB positive result | 0.285 | Â | Calculated |
T-SPOT.TB true positive (PPV) | 1.000 | Â | Calculated |
T-SPOT.TB true negative (NPV) | 0.979 | Â | Calculated |
T-SPOT.TB true positive (PPV) given a positive TST | 1.000 | Â | Calculated |
T-SPOT.TB negative (NPV) given a positive TST | 0.987 | Â | Calculated |
QFT-GIT sensitivity | 0.89 | 0.85-0.95 | |
QFT-GIT specificity | 0.95 | 0.90-0.97 | |
QFT-GIT positive result | 0.302 | Â | Calculated |
QFT-GIT true positive (PPV) | 0.884 | Â | Calculated |
QFT-GIT true negative (NPV) | 0.953 | Â | Calculated |
QFT-GIT true positive (PPV) given a positive TST | 0.930 | Â | Calculated |
QFT-GIT true negative (NPV) given a positive TST | 0.971 | Â | Calculated |
TST sensitivity | 0.85 | 0.69-0.95 | |
TST specificity | 0.80 | 0.65-0.90 | |
TST positive result | 0.395 | Â | Calculated |
TST true positive (PPV) | 0.646 | Â | Calculated |
TST true negative (NPV) | 0.926 | Â | Calculated |
Start INH treatment | 0.80 | 0.55-0.95 | [47] |
Develop severe INH hepatitis | 0.003 | 0.003-0.041 | |
Death due to hepatitis | 0.00002 | 0.00001-0.0001 | |
Efficacy of 3 months INH (LTBI fully cured) | 0.21 | 0.1-0.3 | |
LTBI not cured (with 3 months INH) | 0.79 | 0.7-0.9 | |
Efficacy of 6 months INH (LTBI fully cured) | 0.65 | 0.5-0.93 | |
LTBI not cured (with 6 months INH) | 0.35 | 0.07-0.5 | |
Post exposure TB | 0.025 | 0.01-0.05 | |
TB remains latent | 0.975 | 0.95-0.99 | |
Cost (British Pounds; £s) |  |  |  |
T-SPOT.TB (kit, consumables and processing) + phlebotomy | 55.00 | 45.00-100.00 | Test cost from Royal Free Hospital, London; Phlebotomy cost from [56] |
TST(cost of disposables, administration and reading) | 16.14 | 8.07-32.28 | |
QFT-GIT (kit, consumables and processing) + phlebotomy | 45.00 | 35.00-80.00 | Test cost from Royal Blackburn Hospital; Phlebotomy cost from [56] |
Treatment for severe INH hepatotoxicity | 629.12 | 314.56-1258.24 | |
3 months INH treatment | 484.38 | 242.19-968.76 | |
6 months INH treatment | 524.59 | 262.30-1049.18 | |
Treatment for active TB | 7619.67 | 3809.84-15239.34 |