Table 2.
Ultrasonic and biochemical screening test diagnostic effectiveness at 28 weeks of gestational age for preterm delivery of a small for gestational age infant (n=3981)
| True positive/false positive | True negative/false negative | Positive likelihood ratio (95% CI) | Negative likelihood ratio (95% CI) | Sensitivity (95% CI) | Specificity (95% CI) | Positive predictive value (95% CI) | Negative predictive value (95% CI) | |
|---|---|---|---|---|---|---|---|---|
| Ultrasonic estimated fetal weight below the tenth percentile | 12/308 | 3647/14 | 5·9 (3·9–9·1) | 0·58 (0·41–0·83) | 46·2% (27·3–66·2) | 92·2% (91·3–93·0) | 3·8% (2·1–6·5) | 99·6% (99·4–99·8) |
| sFLT1/PlGF ratio >5·78 | 19/574 | 3381/7 | 5·0 (3·9–6·4) | 0·31 (0·17–0·59) | 73·1% (51·7–87·3) | 85·5% (84·4–86·6) | 3·2% (2·1–5·0) | 99·8% (99·6–99·9) |
| Ultrasonic estimated fetal weight below the tenth percentile and sFLT1/PlGF ratio >5·78 | 10/37 | 3918/16 | 41·1 (23·0–73·6) | 0·62 (0·46–0·84) | 38·5% (21·1–59·3) | 99·1% (98·7–99·3) | 21·3% (11·6–35·8) | 99·6% (99·3–99·8) |
| Ultrasonic estimated fetal weight below the tenth percentile and lowecst decile of abdominal circumference growth velocity* | 3/85 | 3852/23 | 5·3 (1·8–15·8) | 0·90 (0·79–1·04) | 11·5% (3·5–32·1) | 97·8% (97·3–98·3) | 3·4% (1·1–10·3) | 99·4% (99·1-99·6) |
| Delphi procedure definition of early fetal growth restriction* | 12/106 | 3747/13 | 17·4 (11·1–27·3) | 0·53 (0·37–0·78) | 48·0% (28·4–68·2) | 97·2% (96·7–97·7) | 10·2% (5·8–17·2) | 99·7% (99·4–99·8) |
Small for gestational age was defined as a customised birthweight below the tenth percentile (see Methods). sFLT1=soluble fms-like tyrosine kinase 1. PlGF=placental growth factor.
*
See appendix for definitions.