Review Article
Interferon-Gamma Release Assays versus Tuberculin Skin Testing for the Diagnosis of Latent Tuberculosis Infection: An Overview of the Evidence
Table 1
Comparison of TST and IGRA regarding several tests' characteristics.
| Test characteristics | TST | QFT | T-SPOT.TB |
| Overall sensitivity [22] | 77% | 78% | 92% | HIV uninfected [9] | | 84% | 88% | HIV infected [18] | | 65% | 68% | Overall specificity [22] | 97% | 98% | 93% | HIV uninfected | | NA | NA | HIV infected [18] | | 52% | 61% | Decreased specificity if BCG vaccinated? | Yes, particularly if done after infancy or repeatedly [22] | |
No effect [22] | Prone to nonspecific variations in test results? | Yes, from reader variability [10] | |
Yes, from innumerous factors [23–28] | Thresholds for conversions evidence based? | Yes [15] | No | No | Prone to conversions? | Yes, mostly due to TB exposure | |
Yes (high when only negative-positive definitions are used) [29] | Prone to reversions? | Yes [29] | |
High in individuals with weak IGRA positivity and discordance with TST [29] | Boosting? | Yes [15] | |
Yes, possibly if given 3 days after performing TST [24] | Conversion associated with risk of progression to active TB? | Yes (strong evidence) | |
No direct evidence | Ability to detect those at high risk of developing active TB | Weak [30, 31] | |
Weak [30, 31] | Preventive treatment of individuals with conversion reduces risk of progression to active TB? | Yes [19, 20] | |
No evidence |
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