The use of electroconvulsive therapy (ECT) en bloc in Denmark: a nationwide register-based study

Objective: Electroconvulsive therapy (ECT) en bloc is defined as ECT administered on 2–3 consecutive days. In Denmark, ECT en bloc is recommended for severe conditions such as catatonia, treatment-resistant mania/psychosis, or imminent risk of suicide. To our knowledge, there are no recent reports on the use of ECT en bloc in clinical practice. Here, we provide such a report. Methods: We characterized the use of ECT en bloc in the period from 2006-2019 based on data from Danish national registers. Furthermore, we compared mortality rates between patients receiving ECT en bloc and patients receiving standard regimen ECT (not en bloc). Results: We identified 2173 patients who received a total of 2734 ECT en bloc treatment courses in Denmark in the period from 2006 to 2019 (6% of the total number of ECT treatment courses). The use of ECT en bloc was stable over the study period (range: 138–196 patients per year). The most common treatment indications were unipolar depression (41%), psychotic disorder (23%), and bipolar disorder (20%). The vast majority (90%) received ECT en bloc voluntarily. The 1-year mortality rate ratio for ECT en bloc compared to standard regimen ECT was 1.42 (95%CI: 1.03–1.95). Conclusion: The use of ECT en bloc in Denmark is stable both in terms of the number of patients treated and treatment indications. In keeping with ECT en bloc being used for severe conditions, those receiving this treatment have a higher mortality rate compared to those receiving standard ECT, warranting careful monitoring during follow-up.