Key Takeaways
Extended Takeaways
- In this 1-year naturalistic cohort, the 25th percentile time to recurrence/relapse of any mood episode was 71 days in bipolar I disorder versus 183 days in bipolar II disorder, suggesting a clinically meaningful separation in early relapse timing after lamotrigine initiation.
- The between-diagnosis advantage was driven by mania-related outcomes rather than depressive outcomes: time to recurrence/relapse of mania-related episodes differed significantly (P = .0110), while time to major depressive episodes did not (P = .2468).
- On multivariable Cox analysis, diagnosis was the only selected predictor of time to recurrence/relapse, with a hazard ratio in BPI = 1.4506 for BPII and 95% CI, 1.0893-1.9316; P = .0109, despite baseline differences in concomitant lithium, valproate sodium, atypical antipsychotic, and antidepressant use.
- Baseline prescribing patterns suggest lamotrigine was often added to more complex regimens in bipolar I disorder, where lithium use was 47.6% versus 26.3%, valproate sodium 25.1% versus 16.5%, and atypical antipsychotics 51.3% versus 31.6%, yet bipolar II disorder still showed longer time to recurrence/relapse.
- Median daily lamotrigine doses were broadly similar between groups at 106.8 mg/d in bipolar I disorder and 136.2 mg/d in bipolar II disorder, so the observed difference in maintenance outcomes was not explained by a clear dose advantage in bipolar II disorder.
- Adverse drug reactions were comparable in bipolar I disorder and bipolar II disorder at 22.0% (n = 42/191) and 21.8% (n = 87/399), and skin disorders were 11.5% in both groups; these data support considering bipolar II disorder patients for lamotrigine maintenance without expecting a worse overall safety burden than bipolar I disorder.
