Table 3 Early course differences between patients diagnosed with bipolar I disorder (N = 587) and bipolar II disorder (N = 221). Pearson’s chi-squared tests (or Fisher’s exact test [*]) has been used for categorical variables, Wilcoxon rank-sum test for continuous variables. P < 0.05 are shown in bold. Pairwise Fisher’s exact test was used for post-hoc comparisons of multinomial variables, using Benjamini–Hochberg procedure as false discovery rate (FDR) correction method. Pairwise significant differences (FDR-p < 0.05) between individual categories are indicated with lowercase letters. Abbreviations: DM = depressive-(hypo)manic; M = median; MD = (hypo)manic-depressive; IQR = interquartile range; SMD = standardized mean difference

Episode duration (weeks)

8.00 [4.00, 20.00]

12.00 [4.00, 24.50]

0.160

0.083

Episode polarity*

0.697

< 0.001

 (Hypo)mania

143 (33.6)

20 (13.6)

a,b,c

 MD biphasic cycle

31 (7.3)

0 (0.0)

d,e,f

 Major depression

217 (50.9)

107 (72.8)

a,d

 Minor depression

19 (4.5)

11 (7.5)

b,e

 DM biphasic cycle

8 (1.9)

7 (4.8)

c,f

 Mixed state/Rapid cycling

8 (1.9)

2 (1.4)

Psychotic features

85 (31.6)

3 (2.8)

0.828

< 0.001

Complete remission

266 (76.0)

100 (77.5)

0.036

0.821

Treatment setting

0.616

< 0.001

 Not treated

117 (31.8)

69 (53.1)

a,b

 Outpatient

84 (22.8)

37 (28.5)

a

 Inpatient

167 (45.4)

24 (18.5)

b

Early course (up to the fifth episode)

First cycle length (time from onset to first recurrence)

0.367

0.020

 8 to 48 weeks

75 (21.6)

14 (12.4)

a

 52 to 100 weeks

74 (21.3)

21 (18.6)

 104 to 204 weeks

71 (20.4)

21 (18.6)

 209 to 416 weeks

65 (18.7)

21 (18.6)

 417 or more weeks

63 (18.1)

36 (31.9)

a

Average episode duration

8.00 [4.60, 14.00]

10.50 [5.00, 19.95]

0.291

0.015

History of early hospitalization

288 (80.0)

54 (46.6)

0.740

< 0.001

History of incomplete remission

145 (42.2)

52 (44.4)

0.046

0.745

Proportion of (hypo)manic episodes (%)

0.40 [0.20, 0.60]

0.20 [0.00, 0.40]

0.673

< 0.001

Proportion of depressive episodes (%)

0.40 [0.20, 0.60]

0.67 [0.50, 0.80]

0.895

< 0.001

Proportion of other episodes (%)

0.00 [0.00, 0.31]

0.00 [0.00, 0.20]

0.270

0.025

(Hypo)manic-depressive cycles

94 (23.4)

6 (4.5)

0.566

< 0.001

Depressive-(hypo)manic cycles

45 (11.2)

16 (12.0)

0.026

0.916

Rapid cycling

29 (7.2)

22 (16.5)

0.291

0.003

Psychotic features

183 (67.5)

12 (11.9)

1.383

< 0.001

Antidepressant treatment

148 (57.1)

80 (79.2)

0.488

< 0.001

Antipsychotic treatment

142 (54.8)

22 (21.8)

0.723

< 0.001

Benzodiazepine treatment

101 (39.0)

31 (30.7)

0.175

0.178

Psychotherapy

30 (11.6)

9 (8.9)

0.088

0.586

Electroconvulsive therapy

30 (11.6)

9 (8.9)

0.088

0.586

Mood stabilizer treatment

197 (76.1)

62 (61.4)

0.321

0.008

History of early treatment*

251 (96.9)

93 (92.1)

0.213

0.082

First episode of (hypo)manic or mixed polarity

0.678

< 0.001

 First episode

190 (44.6)

29 (19.7)

a,b,c

 Second episode

127 (29.8)

38 (25.9)

a,d,e

 Third or fourth episode

68 (16.0)

44 (29.9)

b,d

 Fifth episode or more

41 (9.6)

36 (24.5)

c,e