Age group	Group difference in improvement over 12 months (intervention minus control) (95% CI)	P value
3 to 7 months	4.2 (1.7 to 6.8)	0.0009
8 to 12 years	6.7 (2.1 to 11.2)	0.005
13 to 18 years	9.9 (4.3 to 15.5)	< 0.0001