Table 5 Logistic regression models predicting bipolar II disorder. P < 0.05 are shown in bold. Abbreviations: AIC = Akaike Information Criterion; CI = confidence interval; OR = odds ratio; ref = reference category

(Intercept)

-2.165

0.11 (0.04–0.32)

< 0.001

-2.001

0.14 (0.06–0.31)

< 0.001

Age (years)

0.012

1.01 (0.98–1.04)

0.387

-

-

-

Sex [ref = female]

-0.159

0.85 (0.59–1.22)

0.387

-

-

-

Age at onset of mania or hypomania (years)

0.012

1.01 (0.99–1.04)

0.367

0.020

1.02 (1.00-1.04)

0.012

Illness duration (years)

-0.009

0.99 (0.96–1.02)

0.553

-

-

-

Predominant polarity [ref = balanced]

 Depressive

0.396

1.49 (0.89–2.49)

0.133

-

-

-

 Manic

-0.543

0.58 (0.26–1.31)

0.189

-

-

-

Number of lifetime isolated (hypo)manic episodes [ref = two episodes]

 None

0.669

1.95 (0.94–4.07)

0.074

1.017

2.76 (1.41–5.43)

0.003

 One episode

0.604

1.83 (1.01–3.31)

0.046

0.81

2.25 (1.29–3.91)

0.004

 Multiple recurrence (3 to 6 episodes)

-0.124

0.88 (0.48–1.63)

0.690

-0.296

0.74 (0.42–1.32)

0.309

 Highly recurrent (hypo)mania (7 or more)

0.381

1.46 (0.64–3.35)

0.367

-0.134

0.87 (0.46–1.67)

0.683

Number of lifetime isolated depressive episodes [ref = recurrent depression (2 to 3 episodes)]

 None

-0.687

0.50 (0.15–1.65)

0.256

-1.207

0.30 (0.11–0.81)

0.017

 One episode

-0.285

0.75 (0.37–1.53)

0.433

-0.477

0.62 (0.33–1.17)

0.138

 Multiple recurrence (4 to 7 episodes)

0.928

2.53 (1.35–4.75)

0.004

0.962

2.62 (1.61–4.24)

< 0.001

 Highly recurrent depression (8 or more episodes)

1.515

4.55 (1.91–10.86)

0.001

1.448

4.25 (2.38–7.59)

< 0.001

Number of lifetime illness episodes (including multiphasic cycles, mixed episodes, continuous cycling) [ref = average number of episodes (5 to 9 episodes)]

 Low number of episodes (1 to 4 episodes)

0.181

1.20 (0.61–2.35)

0.600

-

-

-

 High number of episodes (10 to 15 episodes)

-0.256

0.77 (0.41–1.47)

0.433

-

-

-

 Very high number of episodes (16 or more)

-0.518

0.60 (0.22–1.60)

0.304

-

-

-

Frequency of episodes [ref = rapid cycling (more than 4 episodes per year)]

 Low recurrence (at most every 4 years)

-0.119

0.89 (0.44–1.80)

0.742

0.001

1 (0.55–1.83)

0.997

 Average recurrence (at most every 2 years)

-0.204

0.82 (0.45–1.46)

0.493

-0.131

0.88 (0.51–1.5)

0.631

 High recurrence (at most every year)

-0.579

0.56 (0.31–1.03)

0.061

-0.52

0.59 (0.34–1.05)

0.072

 Very high recurrence (more than 1 episode/year)

-0.806

0.45 (0.22–0.92)

0.028

-0.798

0.45 (0.22–0.91)

0.026

Lifetime history of multiphasic cycles [ref = absent]

-0.376

0.69 (0.45–1.04)

0.076

-0.445

0.64 (0.43–0.95)

0.027