Table 1.

Lifetime prevalence and age-of-onset of DSM-IV/CIDI bipolar disorder (BPD) in the total sample (n = 9282)

	Any BPD		BP-I		BP-II		Sub-threshold BPD
	%	(se)	%	(se)	%	(se)	%	(se)
Prevalence
Lifetime	4.4	(0.2)	1.0	(0.1)	1.1	(0.1)	2.4	(0.2)
12-month	2.8	(0.2)	0.6	(0.1)	0.8	(0.1)	1.4	(0.2)
Age-of-onset1
Mean (se)	20.8	(0.6)	18.2	(1.2)	20.3	(0.9)	22.2	(0.9)
IQR2	12.6-24.9		12.3-21.2		12.1-24.0		13.0-28.3

¹Retrospectively reported age-of-onset of first manic/hypomanic or depressive episode. The means differ significantly across the three BPD subgroups at the .05 level using a two-sided test (χ²2 = 7.8, p = .020).

²Inter-quartile range (IQR) is the range between the 25^th and 75^th percentiles on the age-of-onset distribution.