Table 1 Characteristics of prospective validation studies published for the highest-quality clinical prediction rules

 Kuppermann 2009 [3]

25 PED in the US

8627 patients

(2216 < 2y; 6411 > 2y)

Same as original rule

ciTBI = 88

(25 < 2y; 63 > 2y)

< 2y

SENS 100 (95% CI 86.3–100)

SPEC 53.7 (95% CI 51.6–55.7)

NPV 100 (95% CI 99.7–100)

PPV 2.4 (95% CI 1.6–3.5)

> 2y

SENS 96.8 (95% CI 89.0–99.6)

SPEC 58.2 (95% CI 57.0–59.4)

NPV 99.95 (95% CI 99.80–99.99)

PPV 2.2 (95% CI 1.7–2.9)

Internal validation

 Schonfeld 2014 [95]

1 PED in the US;

1 PED in Italy

2428 patients

(956 < 2y; 1472 > 2y)

Same as original rule

ciTBI = 19

(6 < 2y; 13 > 2y)

Positive CT = 69

< 2y

SENS 100 (95% CI 64.3–100)

SPEC 43.2 (95% CI 40–46.3)

PPV 1.7 (95% CI 0.6–3.2)

NPV 100 (95% CI 99.4–100)

> 2y

SENS 100 (95% CI 79.4–100)

SPEC 48.3 (95% CI 45.8–50.9)

PPV 2.0 (95% CI 1.1–3.2)

NPV 100 (95% CI 99.8–100)

- Low number of study outcome (n = 19; NS = 0)

- 17.5% of record retrospectively collected following prospective implementation of the rule

- Incomplete clinical follow up

 Easter 2014 [96]

1 PED in the US

1009 patients

Included GCS = 13 (0.4%)

ciTBI = 21

SENS 100 (95% CI 84–100)

SPEC 62 (95% CI 59–66)

LR+ 2.7 (95% CI 2.5–2.9)

LR- 0 (95% CI 0-undefined)

Included patients with GCS = 13 (but only 4 patients)

Only overall rule performance reported

 Osmond 2012 [98]

9 PED in Canada

4060 patients

Same as original rule

Injury requiring NS = 23

Acute brain injury on CT = 197

For the four high risk factors - for injuries needing NS

SENS 87 (95% CI 68–98)

SPEC 87 (95% CI 86–88)

PPV 3.6 (95% CI 2.3–5.5)

NPV 99.9 (95% CI 99.8–100)

For the 7 CATCH predictors - for acute brain injury on CT

SENS 98 (95% CI 95–99)

SPEC 65 (95% CI 64–67)

PPV 12.7 (95% CI 11.1–14.4)

NPV 99.8 (95% CI 99.6–99.9)

Abstract form only. (Complete accuracy measures calculated based on the numbers provided to the authors to the NICE head injury guideline working group – see Table 15 of the NICE guideline appendices)

Predicted CT rate: 14% for identifying injuries that require neurological intervention; 38% for acute brain injury on CT

 Easter 2014 [96]

1 PED in the US

1009 patients

not selected based on CATCH symptoms; presenting within 24 h

Injury requiring NS = 4

Any injury on CT = 52

For injury requiring NS

SENS 75 (95% CI 19–99)

SPEC 43 (95% CI 40–46)

LR+ 1.3 (95% CI 0.7–2.3)

LR- 0.6 (95% CI 0.1–3.2)

For any injury on CT

SENS 90 (95% CI 79–97)

SPEC 45 (95% CI 42–48)

LR+ 1.6 (95% CI 1.5–1.8)

LR- 0.4 (95% CI 0.3–0.6)

Different inclusion criteria compared with original rule

Outcome not exactly as in original rule

 Easter 2014 [96]

1 PED in the US

1009 patients up to 18 years of age; presenting within 24 h

Injury requiring NS = 4

Any injury on CT = 52

For injury requiring NS

SENS 75 (95% CI 19–99)

SPEC 84 (95% CI 81–86)

LR+ 4.5 (95% CI 2.5–8.2)

LR- 0.3 (95% CI 0.1–1.6)

For any injury on CT

SENS 64 (95% CI 47–79)

SPEC 86 (95% CI 83–88)

LR+ 4.4 (95% CI 3.3–5.9)

LR- 0.4 (95% CI 0.3–0.6)

Different age limit compared with orginal rule

Outcomes not exactly as in original rule