Table 1.

Demographic and clinical characteristics of study patients with bipolar I (BPI) disorder^a.

	Discovery group			Replication group
	Onset ≤ 20 (N = 516)	Onset > 20 (N = 790)	P value	Onset ≤ 20 (N = 153)	Onset > 20 (N = 320)	P value
Sex			0.843			0.938
Male	229 (44.4%)	355 (44.9%)		74 (48.4%)	156 (48.7%)
Female	287 (55.6%)	435 (55.1%)		79 (51.6%)	164 (51.3%)
Age at onset	17.02 ± 2.54	31.83 ± 9.29	<0.001	17.65 ± 1.99	32.05 ± 9.03	<0.001
Age at recruitment	37.56 ± 11.79	41.84 ± 11.63	<0.001	37.56 ± 12.52	47.23 ± 12.35	<0.001
With psychotic features (%)	465 (90.8%)	665 (84.2%)	0.002	138 (90.2%)	259 (80.9%)	0.010
With suicide attempt	264 (51.1%)	345 (43.7%)	0.008	64 (41.8%)	110 (34.3%)	0.116
First mood episode			0.005			0.685
Mania	283 (54.8%)	495 (62.7%)		92 (60.1%)	205 (64.1%)
Depression	233 (45.2%)	295 (37.3%)		61 (39.9%)	115 (35.9%)

^aIncluding early-onset (≤20) and non-early-onset (>20) patients in both discovery and replication groups.