How to Use Lamotrigine Maintenance in Bipolar II Disorder
How should clinicians use this study when deciding whether lamotrigine is an appropriate maintenance treatment for bipolar II disorder?
Patients with bipolar II disorder often have recurrent depressive and hypomanic episodes and need maintenance strategies that reduce relapse burden over time. This article addresses a practical prescribing decision by comparing 1-year recurrence or relapse outcomes with lamotrigine in bipolar II disorder versus bipolar I disorder in routine clinical care.
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Confirm the bipolar subtype
Apply this guide only after the patient has been diagnosed with bipolar I disorder or bipolar II disorder according to DSM-IV-TR categories used in the study. The article's main clinical comparison is diagnosis-specific, and the observed maintenance advantage with lamotrigine was associated with bipolar II disorder rather than bipolar I disorder.
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Use lamotrigine when recurrence prevention is the treatment goal
The study evaluated lamotrigine started in routine practice specifically to prevent recurrence or relapse of mood episodes over a 1-year observation period. When maintenance treatment is the immediate clinical objective, the findings support considering lamotrigine as a suitable option in bipolar II disorder.
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Counsel that bipolar II showed longer time to any recurrence or relapse
Explain that lamotrigine was associated with a significantly longer time to recurrence or relapse of any mood episode in bipolar II disorder than in bipolar I disorder, with log-rank P = .0103. The estimated 25th percentile time to recurrence or relapse was 183 days in bipolar II disorder versus 71 days in bipolar I disorder.
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Set expectations about which episodes drove the difference
Tell patients and treating teams that the between-diagnosis advantage was driven by mania-related outcomes rather than depressive outcomes. Lamotrigine significantly prolonged time to recurrence or relapse of mania-related episodes, including hypomanic episodes, in bipolar II disorder compared with bipolar I disorder (P = .0110), while no between-group difference was seen for major depressive episodes (P = .2468).
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Do not attribute the apparent bipolar II advantage to co-treatment alone
The bipolar I and bipolar II groups differed in concomitant treatment patterns at baseline, with more lithium, valproate sodium, and atypical antipsychotic use in bipolar I disorder and more antidepressant use in bipolar II disorder. Even so, Cox proportional hazards modeling selected diagnosis as the only influential factor for time to recurrence or relapse, with hazard ratio 1.4506 and 95% CI 1.0893-1.9316; P = .0109.
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Monitor for recurrence or relapse at each visit
In the study, patients were asked at every visit whether any mood episode had recurred after starting lamotrigine. If recurrence occurred, clinicians recorded the type of episode, the time of onset, and whether and when it remitted; recurrence timing was based on the first subsequent mood episode after lamotrigine initiation, or after remission if a mood episode was present at baseline.
Clinical Considerations
- This was a naturalistic observational study without a control group or blinding, so placebo effects and residual confounding cannot be excluded.
- The authors state they cannot completely rule out the possibility that bipolar I patients were inherently at greater risk of recurrence than bipolar II patients.
- Patients were not registered consecutively, which may have introduced sample selection bias.
- The findings come from Japanese inpatients and outpatients prescribed lamotrigine for the first time in routine practice, which may limit generalizability.
Bottom Line
For maintenance treatment aimed at preventing recurrence or relapse, lamotrigine is a particularly strong option to consider in bipolar II disorder because this study found longer relapse-free time in bipolar II than in bipolar I disorder.
