Table 5.
Quality assessment of both commercial IGRAs
| IGRA | Component of within-test variability | Description | No. of subjects (total no. of measures) | Intraclass correlation coefficient of continuous measures (95% CI) |
|---|---|---|---|---|
| QFTa | Test-retest reproducibilityb | Duplicate 1 versus duplicate 2 | 35 (70) | 0.996 (0.992–0.998) |
| ELISA reader reliability | Repeated readings of optical density at 0, 5, 15, 30, and 60 min | 35 (175) | 0.998 (0.997–0.999) | |
| T-SPOT | Test-retest reproducibilityb | Duplicate 1 versus duplicate 2 | 8 (16) | 0.993 (0.967–0.999) |
a
The correlation coefficient (r) of the standard curve, which was calculated from the mean absorbance values of the internal standards, was >0.999 for each QFT ELISA run.
b
There was perfect agreement of all dichotomous measures (raw, 100%; kappa coefficient, 1.000).