Table 1.

Frequency, mean age, and ratio of boys to girls at inclusion

Centre	Frequency	Mean age (years)	Sex ratio (boys/girls)
1	30	11.1	1.14
2	31	11.2	2.88
3	17	11.8	1.43
4	9	12.3	0.80
5	19	13.9	0.36
6	13	10.9	0.44
7	9	14.2	0.50
8	8	11.7	1.67
9	6	9.8	0.50
10	6	11.5	2.00
11	3	12.5	0.50
Overall	151	11.8	1.04