Table 2.
Sensitivity and specificity of oral swab samples for detection of dengue virus-specific antibody and NS1 antigen in acute dengue patients
| At enrollment | At discharge | |||||
|---|---|---|---|---|---|---|
| HTD (n = 66) | TGH (n = 49) | Total (n = 116) | HTD (n = 59) | TGH (n = 47) | Total (n = 106) | |
| IgM | ||||||
| Plasma positive (of which OS positive) | 3 (0) | 1 (0) | 4 (0) | 56 (44) | 27 (13) | 83 (57) |
| Sensitivity (95% CI) | 0% | 0% | 0% | 78.6% (67.8–89.3) | 48.1% (29.3–67.0) | 68.7% (58.7–78.7) |
| Plasma negative (of which OS negative) | 62 (61) | 43 (43) | 105 (104) | 1 (1) | 20 (20) | 21 (21) |
| Specificity (95% CI) | 98.4% (95.3–100) | 100% | 99.0% (97.2–100) | 100% | 100% | 100% |
| IgG | ||||||
| Plasma positive (of which OS positive) | 2 (0) | 2 (0) | 4 (0) | 38 (37) | 24 (20) | 62 (57) |
| Sensitivity (95% CI) | 0% | 0% | 0% | 97.4% (92.3–100) | 83.3% (68.4–98.2) | 91.9% (85.2–98.7) |
| Plasma negative (of which OS negative) | 63 (62) | 47 (47) | 110 (109) | 17 (14) | 22 (22) | 39 (36) |
| Specificity (95% CI) | 98.4% (95.3–100) | 100% | 99.1% (97.3–100) | 82.4% (64.2–100) | 100% | 92.3% (83.9–100) |
| NS1 | ||||||
| Plasma positive (of which OS positive)† | 62 (38) | 23 (17) | 85 (55) | |||
| Sensitivity (95% CI) | 61.3% (49.2–73.4) | 73.9% (56.0–91.9) | 64.7% (54.5–74.9) | |||
| Plasma negative (of which OS negative) | 0 (0) | 24 (23) | 24 (23) | |||
| Specificity (95% CI) | n/a | 95.8% (87.8–100) | 95.8% (87.8–100) | |||
*
OS = oral swab; 95% CI = 95% confidence interval; HTD = Hospital for Tropical Diseases; TGH = Tien Giang Provincial Hospital.
†
Insufficient OS sample available for NS1 testing for four participants.
Note: except as noted in (†) where plasma positive and plasma negative do not sum to total number of samples, this is because plasma samples with equivocal results in an assay have been excluded from the calculations for that assay.