Table 2 Lifetime clinical 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: M = median; IQR = interquartile range; SMD = standardized mean difference

Clinical course*

0.487

< 0.001

 Single episode

14 (3.1)

0 (0.0)

a,b

 Completely episodic

155 (34.2)

36 (21.1)

c

 Episodic with residual symptoms

147 (32.5)

50 (29.2)

d

 Chronic fluctuating

115 (25.4)

73 (42.7)

b,c,d

 Chronic/Deteriorating/Continuous cycling

22 (4.9)

12 (7.0)

a

Predominant polarity

0.735

< 0.001

 Manic

156 (28.6)

12 (6.0)

a,b

 Balanced

229 (42.0)

75 (37.3)

a,c

 Depressive

160 (29.4)

114 (56.7)

b,c

Number of lifetime isolated (hypo)manic episodes

0.383

< 0.001

 None

53 (9.8)

31 (15.5)

a,b

 One episode

114 (21.0)

62 (31.0)

c,d

 Two episodes

107 (19.7)

28 (14.0)

a,c

 Multiple recurrence (3 to 6 episodes)

157 (29.0)

35 (17.5)

b,d

 Highly recurrent (hypo)mania (7 or more episodes)

111 (20.5)

44 (22.0)

Number of lifetime isolated depressive episodes

0.676

< 0.001

 None

71 (13.1)

5 (2.5)

a,b,c

 One episode

104 (19.2)

18 (9.0)

d,e

 Recurrent depression (2 to 3 episodes)

154 (28.4)

41 (20.5)

a,f,g

 Multiple recurrence (4 to 7 episodes)

125 (23.0)

67 (33.5)

b,d,f

 Highly recurrent depression (8 or more episodes)

89 (16.4)

69 (34.5)

c,e,g

Number of lifetime illness episodes (including multiphasic cycles, mixed episodes, continuous cycling)

0.238

0.038

 Low number of episodes (1 to 4 episodes)

174 (32.6)

49 (25.3)

a

 Average number of episodes (5 to 9 episodes)

195 (36.5)

69 (35.6)

 High number of episodes (10 to 15 episodes)

86 (16.1)

31 (16.0)

 Very high number of episodes (16 or more episodes)

79 (14.8)

45 (23.2)

a

Frequency of episodes

0.360

0.001

 Low recurrence (at most every 4 years)

134 (25.0)

45 (23.1)

a

 Average recurrence (at most every 2 years)

155 (28.9)

51 (26.2)

b

 High recurrence (at most every year)

101 (18.8)

25 (12.8)

c

 Very high recurrence (more than 1 episode per year)

57 (10.6)

14 (7.2)

d

 Rapid cycling course (more than 4 episodes per year)

89 (16.6)

60 (30.8)

a,b,c,d

Lifetime history of rapid cycling

89 (25.1)

60 (46.5)

0.457

< 0.001

Lifetime history of multiphasic cycles

183 (36.0)

48 (26.7)

0.201

0.030

Lifetime history of psychosis

1.389

< 0.001

 No history of psychosis

79 (26.1)

88 (81.5)

a,b

 Mood-congruent psychosis

172 (56.8)

10 (9.3)

a,c

 Mood-incongruent/outside episodes

52 (17.2)

10 (9.3)

b,c

Lifetime history of suicide attempts

0.045

0.881

 No history of suicide attempts

282 (63.9)

110 (61.8)

 Single attempt

93 (21.1)

40 (22.5)

 Multiple attempts

66 (15.0)

28 (15.7)