Electroconvulsive therapy (ECT) is effective for unipolar depression but relapse and suicide are significant challenges. Lithium could potentially lower these risks, but is used only in a minority of patients.
This population-based register study used data from the Swedish National Quality Register for ECT and other Swedish national registers. Patients who have received ECT for unipolar depression as in-patients between 2011 and 2016 were followed until death, readmission to hospital or the termination of the study at the end of 2016. Cox regression was used to estimate hazard ratios (HR) of readmission and suicide in adjusted models.
Out of 7350 patients, 56 died by suicide and 4203 were readmitted. Lithium was prescribed to 638 (9%) patients. Mean follow-up was 1.4 years. Lithium was significantly associated with lower risk of suicide (P = 0.014) and readmission (HR 0.84 95% CI 0.75–0.93). The number needed to be treated with lithium to prevent one readmission was 16. In addition, the following factors were statistically associated with suicide: male gender, being a widow, substance use disorder and a history of suicide attempts. Readmission was associated with young age, being divorced or unemployed, comorbid anxiety disorder, nonpsychotic depression, more severe symptoms before ECT, no improvement with ECT, not receiving continuation ECT or antidepressants, usage of antipsychotics, anxiolytics or benzodiazepines, severity of medication resistance and number of previous admissions.