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Table 2 Test Characteristics of Selected HC Thresholds for Diagnosis of Children with IEC or MGCM

From: The test characteristics of head circumference measurements for pathology associated with head enlargement: a retrospective cohort study

A

B

C

D

E

G

H

I

K

L

M

N

Threshold

Number in source population

Number diagnosed with IEC or MGCM

Number above threshold

Number above threshold with IEC or MGCM

Sensitivity

E/C

Specificity

(B-C-(D-E))/(B-C)

Positive predictive value

E/D

Likelihood ratio positive

G/(1-H)

Likelihood ratio negative

(1-G)/H

Number Needed to Screen

B/E

Number Needed to Test

D/E

Above CDC 95th

74,428

85

12,325

39

46%

83%

0.3%

2.8

0.6

1,908

316

Above WHO 95th

74,428

85

18,528

47

55%

75%

0.3%

2.2

0.6

1,584

394

Above PCN 95th

74,428

85

7,694

34

40%

90%

0.4%

3.9

0.7

2,189

226

Above CDC 97th

74,428

85

8,373

34

40%

89%

0.4%

3.6

0.7

2,189

246

Above WHO 97th

74,428

85

13,275

41

48%

82%

0.3%

2.7

0.6

1,815

324

Above PCN 97th

74,428

85

4,532

29

34%

94%

0.6%

5.6

0.7

2,566

156

Above CDC 99.6th

74,428

85

2,030

20

24%

97%

1.0%

8.7

0.8

3,721

102

Above WHO 99.6th

74,428

85

3,438

25

29%

95%

0.7%

6.4

0.7

2,977

138

Above PCN 99.6th

74,428

85

711

13

15%

99%

1.8%

16.3

0.9

5,725

55

Crossed 2 IMPL-CDC

64,015

83

29,206

50

60%

54%

0.2%

1.3

0.7

1,280

584

Crossed 2 IMPL-WHO

64,015

83

22,462

33

40%

65%

0.1%

1.1

0.9

1,940

681

Crossed 2 IMPL-PCN

64,015

83

13,831

26

31%

78%

0.2%

1.5

0.9

2,462

532

Crossed 4 IMPL-CDC

64,015

83

5,727

13

16%

91%

0.2%

1.8

0.9

4,924

441

Crossed 4 IMPL-WHO

64,015

83

4,372

7

8%

93%

0.2%

1.2

1.0

9,145

625

Crossed 4 IMPL-PCN

64,015

83

1,703

6

7%

97%

0.4%

2.7

1.0

10,669

284

  1. IEC (intracranial expansive condition); MGCM (metabolic or genetic condition associated with macrocephaly); CDC (Centers for Disease Control head circumference growth curves); WHO (World Health Organization head circumference growth curves); PCN (primary care network head circumference growth curves); IMPL (multiple percentile lines). The negative predictive value (C-(D-E))/(C-D) was 99.9% for all thresholds. No subjects with the outcome crossed 6 increasing MPL, so rows for that outcome were not included. Point estimates and 95% confidence intervals are presented for the thresholds with the highest and lowest sensitivity and highest positive predictive value. The sensitivity of crossing 2 IMPL on the CDC curve for detecting children with IEC or MGCM who received intervention was 78% (95% CI: 56%, 93%). The sensitivity of crossing 4 IMPL on the PCN curve for detecting children with IEC or MGCM was 7% (95% CI: 3%, 15%). The positive predictive value of ever being above the 99.6th percentile of the PCN curve for detecting children with IEC or MGCM was 1.8% (95% CI: 1.0%, 3.1%).