The effect of lithium variation coefficient on the risk of attack in patients with bipolar disorder: A pilot study.

Background: This study examines the association between the coefficient of variation (%CV) of lithium levels and episode risk and frequency in bipolar patients maintaining serum lithium levels within the therapeutic range.

Methods: We retrospectively reviewed patients with bipolar disorder under care from 2018 to 2022. Inclusion criteria were at least 2 years of follow-up, a minimum of three annual lithium level measurements within the therapeutic range. Patients were categorized based on seizure status. We calculated mean lithium levels, standard deviation (SD), and %CV.

Results: The study included 75 patients (patients with-without episodes, 39-36). Demographic data revealed no significant differences. While mean lithium levels showed no significant disparity between groups, SD and %CV were notably higher in patients with episodes (P < .05). ROC analysis demonstrated AUC values of 0.722 (95% CI: 0.607-0.836 P = .001) for %CV and 0.709 (95% CI: 0.593-0.826; P = .002) for SD. The optimal %CV cutoff was 17.39, with 67% sensitivity and 69% specificity. A weak correlation was found between %CV and the number of episodes (P = .001, r = 0.376). The post-hoc power analysis for this study was 0.78.

Conclusions: Despite acceptable lithium levels, patients with recent episodes exhibited significant lithium level fluctuations. Integrating %CV with real-time lithium measurements during bipolar disorder follow-up may enhance clinical monitoring and seizure prediction.