TABLE 2.
Prevalence of VA deficiency calculated with the use of VA TLR and SR concentrations and specificity of SR as an indicator of VA deficiency in Thai and Zambian children, as well as in Zambian children adjusted for infection status1
| Thai children (n = 37) | Zambian children (n = 128) | Zambian children, adjusted for infection (n = 128) | |
| Prevalence of VA deficiency, by indicator | |||
| VA TLR | 24 (65) | 0 | 0 |
| Serum retinol | 0 | 22 (17.2) | 3 (2.3) |
| Cannot be determined | 0 | 0 | 16 (12.5)2 |
| True positives (TLR+, SR+) | 0 | 0 | 0 |
| False positives (TLR−, SR+) | 0 | 22 (17.2) | 3 (2.3) |
| False negatives (TLR+, SR−) | 24 (65) | 0 | 0 |
| True negatives (TLR−, SR−) | 13 (35) | 106 (82.8) | 109 (85.2) |
| Cannot be determined | 0 | 0 | 16 (12.5) |
| Sensitivity3 | 0 | NC | NC |
| Specificity4 | 100 | 82.8 | 97.3 |
1
Values are percentages or n (%). Both TLR+ and SR+: positive for VAD according to that indicator. Both TLR– and SR−: negative for VAD according to that indicator. CRP, C-reactive protein; NC, not calculable (divided by zero); SR, serum retinol; TLR, total liver reserve; VA, vitamin A; VAD, vitamin A deficiency.
2
Could not be adjusted for infection because of missing CRP values.
3
Calculated as true positives/(true positives + false negatives).
4
Calculated as true negatives/(true negatives + false positives).