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
| Bipolar I disorder | Bipolar II disorder | |||
|---|---|---|---|---|
| First episode features | N (%) / M [IQR] | N (%) / M [IQR] | SMD | p |
| 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 |