Table 3.
Test Characteristics of Selected HC Thresholds for Diagnosis of Children with IEC or MGCM Requiring Intervention
| A | B | C | D | E | G | H | I | K | L | M | N |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Threshold | Number in source population | Number diagnosed with IEC or MGCM requiring intervention | Number above threshold | Number above threshold with IEC or MGCM requiring intervention |
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 | 24 | 12,325 | 11 | 46% | 83% | 0.1% | 2.8 | 0.6 | 6,766 | 1,120 |
| Above WHO 95th | 74,428 | 24 | 18,528 | 14 | 58% | 75% | 0.1% | 2.3 | 0.6 | 5,316 | 1,323 |
| Above PCN 95th | 74,428 | 24 | 7,694 | 9 | 38% | 90% | 0.1% | 3.6 | 0.7 | 8,270 | 855 |
| Above CDC 97th | 74,428 | 24 | 8,373 | 9 | 38% | 89% | 0.1% | 3.3 | 0.7 | 8,270 | 930 |
| Above WHO 97th | 74,428 | 24 | 13,275 | 12 | 50% | 82% | 0.1% | 2.8 | 0.6 | 6,202 | 1,106 |
| Above PCN 97th | 74,428 | 24 | 4,532 | 7 | 29% | 94% | 0.2% | 4.8 | 0.8 | 10,633 | 647 |
| Above CDC 99.6th | 74,428 | 24 | 2,030 | 6 | 25% | 97% | 0.3% | 9.2 | 0.8 | 12,405 | 338 |
| Above WHO 99.6th | 74,428 | 24 | 3,438 | 6 | 25% | 95% | 0.2% | 5.4 | 0.8 | 12,405 | 573 |
| Above PCN 99.6th | 74,428 | 24 | 711 | 5 | 21% | 99% | 0.7% | 22.0 | 0.8 | 14,886 | 142 |
| Crossed 2 IMPL-CDC | 64,015 | 21 | 29,206 | 18 | 78% | 54% | 0.1% | 1.7 | 0.4 | 3,566 | 1,623 |
| Crossed 2 IMPL-WHO | 64,015 | 21 | 22,462 | 10 | 43% | 65% | < 0.1% | 1.2 | 0.9 | 6,402 | 2,246 |
| Crossed 2 IMPL-PCN | 64,015 | 21 | 13,831 | 9 | 39% | 78% | 0.1% | 1.8 | 0.8 | 7,113 | 1,537 |
| Crossed 4 IMPL-CDC | 64,015 | 21 | 5,727 | 4 | 17% | 91% | < 0.1% | 1.9 | 0.9 | 16,004 | 1,432 |
| Crossed 4 IMPL-WHO | 64,015 | 21 | 4,372 | 2 | 9% | 93% | 0.1% | 1.3 | 1.0 | 32,008 | 2,186 |
| Crossed 4 IMPL-PCN | 64,015 | 21 | 1,703 | 2 | 9% | 97% | 0.2% | 3.3 | 0.9 | 32,008 | 852 |
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 (increasing 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 IMPL, so rows for that outcome were not included.