Table 1.
Overview household contacts eligible for baseline analysis using different definitions of visit 1 QFT status
| Definition 1 (≥0.2) |
Definition 2a (≥0.35) |
Definition 3 (≥0.7) |
|||||||
|---|---|---|---|---|---|---|---|---|---|
| Definition 1 (≥0.2 IU/ml) | Zambia n (%) |
South Africa n (%) | Definition 2 (≥0.35 IU/ml)a | Zambia n (%) |
South Africa n (%) |
Definition 3 (≥0.7 IU/ml) | Zambia n (%) |
South Africa n (%) |
|
| Positive | 735 (54) | 626 (76) | 669 (49) | 574 (70) | 599 (44) | 504 (61) | |||
| Nil | ≤8.0 | ≤8.0 | ≤8.0 | ||||||
| TBAgNil | ≥0.2 & (≥25% of Nil value) | ≥0.35 & (≥25% of Nil value) | ≥0.7 & (≥25% of Nil value) | ||||||
| Negative | 445 (33) | 182 (22) | 495 (36) | 230 (28) | 551 (40) | 297 (36) | |||
| Nil | ≤8.0 | ≤8.0 | ≤8.0 | ||||||
| TBAgNil | < 0.2 or < 25% Nil | < 0.35 or < 25% Nil | < 0.7 or < 25% Nil | ||||||
| MitogenNil | ≥0.5 | ≥0.5 | ≥0.5 | ||||||
| Indeterminateb | all other values | 185 (14) | 14 (2) | all other values | 201 (15) | 18 (2) | all other values | 215 (16) | 21 (3) |
Footnote: Nil negative control response; TBAgNil antigen response minus negative control response; MitogenNil positive control response minus negative control response
a Manufacturer’s recommended assay cut-off
b The number of indeterminate test results differs depending on the QFT definition used: if a positive value becomes a negative value using a stricter QFT definition, it will only be quantified as negative if the value is accompanied with MitogenNil≥0.5. If not, the value is quantified as indeterminate