Table 3. Diagnostic performance of point of care AF IL-6 concentrations and ELISA AF IL-6 for identification of intra-amniotic infection and/or inflammation and placental lesions consistent with acute inflammation.
| Point of care IL-6 test (cut-off 745 pg/ml) |
ELISA IL-6 (cut-off 2600 pg/ml) |
|||||
|---|---|---|---|---|---|---|
| Outcomes | Diagnostic performance | % (n) | 95% CI | % (n) | 95% CI | |
| Intra-amniotic inflammation [44.1% (60/136)] | Sensitivity | 93.3 (56/60) | (83.8–98) | 100% diagnostic performance. ELISA IL-6 is a gold standard test for the identification of intra-amniotic inflammation | ||
| Specificity | 90.8 (69/76) | (82–96) | ||||
| Positive predictive value | 88.9 (56/63) | (78.4–95.4) | ||||
| Negative predictive value | 94.5 (69/73) | (86.6–98.5) | ||||
| Positive likelihood ratio | 10.1 (93.3/9.2) | (5–21) | ||||
| Negative likelihood ratio | 0.07 (6.7/90.8) | (0.03–0.2) | ||||
| Microbial invasion of the amniotic cavity (MIAC) identified by culture [16.3% (22/136)] | Sensitivity | 90.9 (20/22) | (70.8–98.6) | 81.8 (18/22) | (59.7–94.7) | |
| Specificity | 62.3 (70/114) | (52.7–71.2) | 63.2 (71/114) | (53.6–72.0) | ||
| Positive predictive value | 31.8 (20/63) | (20.6–44.7) | 30.0 (18/60) | (18.9–43.2) | ||
| Negative predictive value | 97.3 (71/73) | (90.4–99.6) | 94.7 (71/76) | (87.1–98.5) | ||
| Positive likelihood ratio | 2.41 (90.9/37.7) | (1.8–3.2) | 2.2 (81.8/36.8) | (1.6–3.0) | ||
| Negative likelihood ratio | 0.15 (9.1/62.3) | (0.04–0.6) | 0.3 (18.2/63.2) | (0.1–0.7) | ||
| Acute inflammatory lesions of placenta (chorioamnionitis or funisitis) [only patients who delivered within three days after amniocentesis were included [57.4% (31/54)]] | Sensitivity | 93.6 (29/31) | (78.5–99) | 93.6 (29/31) | (78.5–99.0) | |
| Specificity | 43.5 (10/23) | (23.2–65.5) | 52.2 (12/23) | (30.6–73.2) | ||
| Positive predictive value | 69.1(29/42) | (52.9–82.3) | 72.5 (29/40) | (56.1–85.4) | ||
| Negative predictive value | 83.3 (10/12) | (51.6–97.4) | 85.7 (12/14) | (57.2–97.8) | ||
| Positive likelihood ratio | 1.7 (93.6/56.5) | (1.1–2.4) | 2.0 (93.6/47.8) | (1.3–3.03) | ||
| Negative likelihood ratio | 0.15 (6.4/43.5) | (0.04–0.6) | 0.12 (6.4/52.2) | (0.03–0.5) | ||
| Acute funisitis [only patients who delivered within three days after amniocentesis were included [38.9% (21/54)]] | Sensitivity | 100 (21/21) | (83.8–100) | 95.2 (20/21) | (76.1–99.2) | |
| Specificity | 36.4 (12/33) | (20.4–54.9) | 39.4 (13/33) | (22.9–57.9) | ||
| Positive predictive value | 50.0 (21/42) | (34.2–65.8) | 50.0 (20/40) | (33.8–66.2) | ||
| Negative predictive value | 100.0 (12/12) | (73.4–100) | 92.9 (13/14) | (66.1–98.8) | ||
| Positive likelihood ratio | 1.57 (100/63.6) | (1.2–2) | 1.6 (95.2/60.6) | (1.2–2.1) | ||
| Negative likelihood ratio | 0 | – | 0.12 (4.8/39.4) | (0.02–0.8) | ||
CI: confidence interval.