Table 2

Sensitivity, specificity, predictive values and likelihood ratio at different foot length cutoffs for low birth weight

FL	Sensitivity	Specificity	PPV	NPV	LR +ve	LR −ve	Euclidean distance
(cm)	(95% CI)	(95% CI)	(95% CI)	(95% CI)	(95% CI)	(95% CI)	Euclidean distance
≤7	100	34.1	35	100	1.5	–	0.69
≤7	(98.5 to 100.0)	(24.3 to 45.0)	(31.7 to 38.5)	100	(1.3 to 1.8)	–	0.69
≤7.1	99.2	43.2	38.3	99.3	1.7	0.02	0.56
≤7.1	(97.1 to 99.9)	(32.7 to 54.2)	(34.1 to 42.7)	(97.4 to 99.8)	(1.5 to 2.1)	(0.005 to 0.08)	0.56
≤7.2	99.2	45.5	39.2	99.4	1.8	0.02	0.54
≤7.2	(97.1 to 99.9)	(34.8 to 56.4)	(34.8 to 43.9)	(97.5 to 99.8)	(1.5 to 2.2)	(0.004 to 0.07)	0.54
≤7.3	98	57.9	45.3	98.8	2.3	0.04	0.42
≤7.3	(95.4 to 99.3)	(47.0 to 68.4)	(39.3 to 51.4)	(97.1 to 99.5)	(1.8 to 3.0)	(0.014 to 0.084)	0.42
≤7.4	97.6	64.8	49.6	98.7	2.8	0.04	0.35
≤7.4	(94.8 to 99.1)	(53.9 to 74.7)	(42.5 to 56.6)	(97.1 to 99.4)	(2.1 to 3.7	(0.017 to 0.084)	0.35
≤7.5	96.4	75	57.8	98.3	3.9	0.05	0.25
≤7.5	(93.2 to 98.3)	(64.6 to 83.6)	(48.8 to 66.3)	(96.8 to 99.1)	(2.7 to 5.5)	(0.025 to 0.093)	0.25
≤7.6	90.3	81.8	63.8	96	4.9	0.1	0.20
≤7.6	(85.9 to 93.7)	(72.2 to 89.2)	(53.1 to 73.4)	(94.1 to 97.2)	(3.2 to 7.7)	(0.08 to 0.18)	0.20
≤7.7	83.1	86.4	68.4	93.5	6.1	0.2	0.21
≤7.7	(77.8 to 87.5)	(77.4 to 92.8)	(56.0 to 78.6)	(91.5 to 95.0)	(3.6 to 10.3)	(0.15 to 0.26)	0.21
≤7.8	71.8	88.6	69.2	89.8	6.3	0.3	0.30
≤7.8	(65.7 to 77.3)	(80.1 to 94.4)	(55.4 to 80.2)	(87.7 to 91.6)	(3.5 to 11.4)	(0.26 to 0.39)	0.30
≤7.9	57.7	93.2	75	86.1	8.5	0.5	0.42
≤7.9	(51.2 to 63.9)	(85.7 to 97.5)	(57.9 to 86.8)	(84.1 to 87.9)	(3.9 to 18.4)	(0.39 to 0.53)	0.42
≤8	47.2	98.9	93.6	84.1	41.5	0.5	0.52
≤8	(40.8 to 53.6)	(93.8 to 100.0)	(67.6 to 99.0)	(82.4 to 85.6)	(5.9 to 292.8)	(0.47 to 0.60)	0.52

cm, centimetre; FL, foot length; LR, likelihood ratio; NPV, negative predictive value; PPV, positive predictive value.