Table 2. CM-1 patient demographics over time.

Demographics	2003 (N=886)	2006 (N=1,133)	2009 (N=1,478)	2012 (N=1,941)	P value
Age, years	10.02±5.57	10.27±5.68	10.65±5.81	10.76±5.71	0.004*
In-hospital mortality, n (%)	9 (1.0)	2 (0.2)	12 (0.8)	10 (0.5)	0.065
CCI	0.16±0.46	0.21±0.50	0.20±0.48	0.25±0.57	<0.001*
Length of stay, days	4.12±2.84	4.36±5.75	3.99±5.52	3.80±4.22	0.016*

*, significance of P<0.05. CM-1, Chiari malformations type 1; CCI, Charlson comorbidity index.