Lamotrigine for acute bipolar depression: An exploratory item‐level analysis

OBJECTIVES: Lamotrigine is used to treat bipolar depression despite inconsistent evidence. Here we present the results of an exploratory item‐level analysis of pooled data from five randomized placebo‐controlled trials of lamotrigine for acute bipolar depression. The goal was to determine if certain depression scale items were more responsive to lamotrigine treatment. METHODS: The pooled sample contained 1072 adult outpatients treated for up to 7–10 weeks. Depressive symptoms were measured with the Hamilton Depression Rating Scale and the Montgomery–Åsberg Depression Rating Scale. Change scores on individual scale items were compared between treatment groups. RESULTS: There were statistically significant effects on items assessing depressed mood/sadness, lack of interest/anhedonia, pessimism/guilt, and anergia/fatigue, on both scales. However, there was marked variation in the baseline symptom prevalence, and items with higher scores at baseline tended to have larger and statistically significant treatment effects. CONCLUSIONS: The results suggested a significant treatment effect on core symptoms of depression. A floor effect appeared to limit the sensitivity of other scale items. Given the exploratory nature of the analysis, firm conclusions cannot be drawn, although the results were consistent with past research. Relying on total depression scale sum scores over targeted assessments of core depressive symptoms may have impeded signal detection in the original trials.