Table 2.
Odds ratios and classification statistics for various BLWR thresholds by gestational age∗
| Group (FGR† cases) | BLWR | OR | 95% CI | SN (%) | 95% CI | SP (%) | 95% CI | NPV (%) | 95% CI | PPV (%) | 95% CI |
| All ages (n = 90) | 2.8 | 2.9 | (1.7–4.7) | 64.4 | (53.7–74.3) | 61.3 | (55.1–67.2) | 83.6 | (77.6–88.5) | 36.0 | (28.6–44.0) |
| 3.0 | 4.0 | (2.4–6.7) | 60.0 | (49.1–70.2) | 72.9 | (67.2–78.2) | 84.3 | (79.0–88.8) | 42.9 | (34.1–52.0) | |
| 3.5 | 6.1 | (3.5–10.6) | 44.4 | (34.0–55.3) | 88.3 | (83.9–91.9) | 82.5 | (77.5–86.7) | 56.3 | (44.0–68.1) | |
| 4.0 | 12.2 | (5.6–26.3) | 32.2 | (22.8–42.9) | 96.2 | (93.2–98.2) | 80.8 | (76.0–84.9) | 74.4 | (57.9–87.0) | |
| 4.5 | 25.0 | (7.2–86.7) | 22.2 | (14.1–32.2) | 98.9 | (96.7–99.8) | 79.0 | (74.2–83.2) | 87.0 | (66.4–97.2) | |
| 5.0‡ | – | – | 20.0 | (12.3–29.8) | 100.0 | (98.6–100.0) | 78.7 | (73.9–82.9) | 100.0 | (81.5–100.0) | |
| 3.3§ | 5.4 | (3.2–9.2) | 51.1 | (40.3–61.8) | 83.8 | (78.8–88.0) | 83.5 | (78.5–87.8) | 51.7 | (40.8–62.4) | |
| <28 weeks gestation (n = 28) | 2.8 | 2.1 | (0.9–4.9) | 60.7 | (40.6–78.5) | 58.2 | (49.9–66.1) | 89.0 | (81.2–94.4) | 21.0 | (12.7–31.5) |
| 3.0 | 3.5 | (1.5–8.0) | 60.7 | (40.6–78.5) | 69.3 | (61.3–76.5) | 90.6 | (83.8–95.2) | 26.6 | (16.3–39.1) | |
| 3.5 | 8.9 | (3.7–21.5) | 57.1 | (37.2–75.5) | 86.9 | (80.5–91.8) | 91.7 | (86.0–95.7) | 44.4 | (27.9–61.9) | |
| 4.0 | 18.1 | (6.3–52.3) | 46.4 | (27.5–66.1) | 95.4 | (90.8–98.1) | 90.7 | (85.1–94.7) | 65.0 | (40.8–84.6) | |
| 4.5 | 35.8 | (7.2–178.0) | 32.1 | (15.9–52.4) | 98.7 | (95.4–99.8) | 88.8 | (83.1–93.1) | 81.8 | (48.2–97.7) | |
| 5.0‡ | – | – | 28.6 | (13.2–48.7) | 100.0 | (97.6–100.0) | 88.4 | (82.7–92.8) | 100.0 | (63.1–100.0) | |
| 3.7§ | 13.2 | (5.2–33.5) | 57.1 | (37.2–75.5) | 90.8 | (85.1–94.9) | 92.1 | (86.5–95.8) | 53.3 | (34.3–71.7) | |
| ≥28 weeks gestation (n = 62) | 2.8 | 3.7 | (1.9–7.1) | 66.1 | (53.0–77.7) | 65.5 | (56.0–74.2) | 77.9 | (68.2–85.8) | 51.3 | (39.8–62.6) |
| 3.0 | 5.2 | (2.7–10.2) | 59.7 | (46.4–71.9) | 77.9 | (69.1–85.1) | 77.9 | (69.1–85.1) | 59.7 | (46.4–71.9) | |
| 3.5 | 5.9 | (2.6–13.1) | 38.7 | (26.6–51.9) | 90.3 | (83.2–95.0) | 72.9 | (64.7–80.0) | 68.6 | (50.7–83.1) | |
| 4.0 | 12.8 | (3.5–45.9) | 25.8 | (15.5–38.5) | 97.3 | (92.4–99.4) | 70.5 | (62.7–77.5) | 84.2 | (60.4–96.6) | |
| 4.5 | 24.2 | (3.0–192.2) | 17.7 | (9.2–29.5) | 99.1 | (95.2–100.0) | 68.7 | (61.0–75.7) | 91.7 | (61.5–99.8) | |
| 5.0‡ | – | – | 16.1 | (8.0–27.7) | 100.0 | (96.8–100.0) | 68.5 | (60.8–75.5) | 100.0 | (69.2–100.0) | |
| 3.0§ | 5.2 | (2.7–10.2) | 59.7 | (46.4–71.9) | 77.9 | (69.1–85.1) | 77.9 | (69.1–85.1) | 59.7 | (46.4–71.9) |
BLWR, brain to liver weight ratio; CI, confidence interval; FGR, fetal growth restriction; NPV, negative predictive value; OR, odds ratio; PPV, positive predictive value; SN, sensitivity; SP, specificity.
*Excludes central nervous system conditions or chromosomal anomalies.
†Defined using weight for gestational age <10th percentile or discordant birth weight/length.
‡Odds ratio calculation not possible as positive predictive grouping consists entirely of true positive cases and the denominator for odds calculation is zero.
§Optimal BLWR for classifying FGR based on Youden's index.