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

Abstract

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.