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. Author manuscript; available in PMC: 2013 Apr 1.
Published in final edited form as: J Pediatr. 2011 Nov 13;160(4):673–678.e1. doi: 10.1016/j.jpeds.2011.09.059

Table 2.

Time 1 and Time 2 descriptive statistics for head shape measures (expressed as z-scoresa) among: children with diagnosed plagiocephaly or brachycephaly, confirmed on 3D imaging (all cases); children with brachycephaly, but not plagiocephaly (isolated brachycephaly); children without diagnosed plagiocephaly or brachycephaly, with some dysmorphology detected on 3D imaging (affected controls); and children without previously diagnosed plagiocephaly or brachycephaly and confirmed absence of cranial dysmorphology on 3D imaging (unaffected controls).

Time 1
All Cases
n=233		 Isolated
Brachycephaly
Cases
n=21		 Affected
Controls
n=70		 Unaffected
Controls
n=167
Posterior Flatness (PF)
 Mean (SD) 2.15 (1.43) 1.29 (0.96) 0.47 (1.20) Ref
 5th percentile −0.09 −0.43 −1.68 −1.63
 25th percentile 1.15 0.68 −0.34 −0.66
 50th percentile 2.11 1.32 0.42 −0.08
 75th percentile 2.96 1.92 1.13 0.68
 95th percentile 4.50 2.52 2.54 1.49
Absolute Asymmetry Score
(AAS)
 Mean (SD) 3.19 (2.17) 0.31 (0.93) 0.56 (1.47) Ref
 5th percentile −0.32 −1.01 −1.18 −1.17
 25th percentile 1.70 −0.32 −0.49 −0.70
 50th percentile 3.13 −0.05 0.27 −0.23
 75th percentile 4.61 1.18 1.61 0.46
 95th percentile 6.84 1.51 3.07 1.92
Oblique Cranial Length
Ratio (aOCLR)
 Mean (SD) 1.17 (1.22) −0.08 (0.40) 0.35 (2.35) Ref
 5th percentile −0.41 −0.61 −0.59 −0.68
 25th percentile 0.40 −0.41 −0.29 −0.49
 50th percentile 1.01 −0.09 −0.02 −0.28
 75th percentile 1.74 0.15 0.42 0.25
 95th percentile 3.09 0.56 1.69 1.15
Cephalic Index (CI)
 Mean (SD) 2.48 (1.46) 3.66 (0.80) 1.19 (1.33) Ref
 5th percentile 0.16 2.71 −1.02 −1.69
 25th percentile 1.40 2.88 0.14 −0.69
 50th percentile 2.52 3.81 2.25 0.06
 75th percentile 3.62 4.13 2.10 0.71
 95th percentile 4.79 4.96 3.34 1.69
Time 2
All Cases
n=221		 Isolated
Brachycephaly
Cases
n=20		 Affected
Controls
n=68		 Unaffected
Controls
n=161
Posterior Flatness (PF)
 Mean (SD) 1.36 (1.12) 1.0 (1.30) 0.32 (0.95) −0.30 (0.94)
 5th percentile −0.42 −1.64 −0.83 −1.68
 25th percentile 0.72 0.22 −0.46 −0.80
 50th percentile 1.33 0.98 0.23 −0.41
 75th percentile 2.07 1.99 0.69 0.25
 95th percentile 3.31 2.95 2.24 1.26
Absolute Asymmetry Score
(AAS)
 Mean (SD) 1.52 (1.62) 0.40 (1.35) 0.12 (1.12) −0.19 (0.85)
 5th percentile −0.83 −0.87 −1.11 −1.14
 25th percentile 0.20 −0.65 −0.61 −0.87
 50th percentile 1.44 −0.15 −0.10 −0.33
 75th percentile 2.46 1.37 0.47 0.31
 95th percentile 4.15 2.97 2.22 1.30
Oblique Cranial Length
Ratio (aOCLR)b
 Mean (SD) 0.94 (0.84) −0.19 (0.41) 0.05 (0.98) −0.23 (0.35)
 5th percentile −0.49 −0.69 −0.57 −0.62
 25th percentile 0.37 −0.50 −0.39 −0.49
 50th percentile 0.92 −0.14 −0.15 −0.28
 75th percentile 1.51 −0.01 0.26 −0.04
 95th percentile 2.38 0.71 0.73 0.39
Cephalic Index (CI)
 Mean (SD) 1.76 (1.31) 2.32 (0.73) 0.65 (1.27) −0.46 (0.88)
 5th percentile −0.13 1.18 −1.02 −1.76
 25th percentile 0.86 1.88 −0.43 −1.10
 50th percentile 1.68 2.26 0.62 −0.43
 75th percentile 2.53 2.80 1.37 0.09
 95th percentile 3.97 3.66 3.02 1.00
a

Scores are expressed in z-score units (mean = 0, standard deviation = 1) using Time 1 scores for unaffected controls as the reference group (e.g., z = observed score - Time 1 unaffected control group mean / Time 1 unaffected control group standard deviation).

b

The aOCLR could not be used for 1 case at Time 2 due to poor 3D photo quality. This did not affect other measures.