Table 1.

Comparisons of demographic characteristics between UK and US data. Results are presented as means (SD), medians (interquartile range, IQR) or n(%). [n] refers to the number of non-missing observations for each given variable in each country/subgroup

	USA		UK		USA-UK Difference (95% CI) *	p-value
N		24835		7933
Number of centers providing data in 2010		237		132
	[n]		[n]
Age (years)	24835		7933
Median (IQR)		16.2 (8.3-25.6)		17.9 (9.3-27.0)	-1.2 (-1.50, -0.90)	<0.001
≥16 years; n(%)		12631 (50.9)		4421 (55.7)	-4.9% (-6.1%, -3.6%)	<0.001
≥18 years; n(%)		11058 (44.5)		3965 (50.0)	-5.5% (-6.7%,-4.2%)	<0.001
Sex	24835		7933
Male; n(%)		12819 (51.6)		4214 (53.1)	-1.5% (-0.2% - 2.8%)	0.020
Race/ethnicity	24835		7837			<0.001
Asian; n(%)		92 (0.4%)		198 (2.5%)
Black; n(%)		842 (3.4%)		29 (0.4%)
White†; n(%)		21594 (87.0%)		7580 (96.7%)
Other††; n (%)		2307 (9.3%)		30 (0.4%)
Age at diagnosis (years)	24727		7856
Median (minmax)		0.4 (0-78.5)		0.3 (0-79.2)		<0.001
< 3 mo; n(%)		10209 (41.3)		3682 (46.9)		<0.001
3-6 mo; n(%)		2743 (11.1)		862 (11.0)		(trend)
6-12 mo; n(%)		2842 (11.5)		649 (8.3)
12 mo – 3 y; n(%)		3251 (13.2)		1047 (13.3)
≥3 y; n(%)		5682 (23.0)		1616 (20.6)
≥18 y; n(%)		1280 (5.2)		469 (6.0)	-0.8% (0.2%, 1.4%)	0.007

^*Where medians are used, differences between the groups are presented as the median difference between values sampled from two groups. This difference is not strictly equal to the difference between the two medians.

^†For the purposes of this analysis (to facilitate comparisons between the US and the UK), white was defined as non-Hispanic whites.

^††For the purposes of this analysis, subjects with Hispanic ethnicity were included in the “other” category