Table 1. Descriptive and demographic characteristics of the examined individuals at baseline and at the two-year follow-up examination.

Study population	Baseline (n = 500)		Follow-up (n = 397)
Demographics
Age (years)	mean	SD	mean	SD
	13.2	1.53	15.0	1.39
Gender	n	%	n	%
Male	232	46.4	176	44.3
Female	268	53.6	221	55.7

SD; standard deviation.