Conditions: Depression
Keywords: Electroconvulsive therapy ECT electrode placement effectiveness cognition autobiographical memory
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 138
Healthy volunteers: no

Brief summary:
Electroconvulsive therapy (ECT) is the most powerful antidepressant treatment available and is often life-saving. There are concerns, however, that standard bitemporal ECT (the most commonly used form of ECT worldwide) causes persisting retrograde amnesia. However, clinical trials have indicated that high-dose unilateral ECT may be as effective as bitemporal ECT but have much less cognitive side-effects.

The trial aims to test the primary experimental hypothesis: High-dose (6 x ST) right unilateral ECT is as effective as (i.e. not inferior to) standard (1.5 x ST) bitemporal ECT for severe depression in terms of Hamilton Depression Rating Score (HDRS) at the end of the treatment course.

Detailed description:
The study is a two-group parallel design randomised controlled non-inferiority trial and has been registered (ISRCTN23577151). Consented patients with major depressive disorder (DSM-IV) will be randomly allocated to a course of bitemporal (BT) ECT (1.5 x ST) or high-dose right unilateral (RUL) ECT (6.0 x ST). To facilitate generalizability of results, the trial takes place under "real world" conditions and so both groups continue usual care and medications during the treatment phase and thereafter. Patients are followed-up for 12 months after completing their allocated course of ECT. Completion of the primary outcome depression-rating measure (i.e. HDRS) and the secondary outcome of most interest (autobiographical memory, using the AMI-SF) will be prioritised in the data collection.

Patients, their treating clinicians and raters are blind to treatment; clinicians administering ECT are not involved in post randomisation assessments or formal data analysis. Success of blinding for patients and raters will be assessed after the second and final treatments. The trial statistician is also blinded to allocation status.

Sample size: In a large series (n = 253) of depressed patients, Petrides et al. (2001) found a mean (SD) reduction in 24-item HDRS of 25.6 (9.4) after treatment with bitemporalT ECT (1.5 x ST). We therefore estimate that 69 patients will be required per treatment group to have 80% power to demonstrate, using a one-sided equivalence t-test at 5% level, that mean reduction in 24-item HDRS achieved using high-dose RUL ECT is no more than 4 points (i.e. equivalent to 3 points on 17-item HDRS) less than that achieved using standard BT ECT, assuming a common within-group SD of change scores of 9.4 and equal expected group mean change scores.

Arms:
arm 1: Modified bilateral ECT (bitemporal electrode positions) twice weekly at 1.5 times the seizure threshold. Methohexitone (0.75-1.0 mg/kg) is used for anaesthesia with suxamethonium (0.5-1.0mg/kg) for muscle relaxation. arm 2: High-dose right modified unilateral ECT twice weekly at 6 times the seizure threshold. Methohexitone (0.75-1.0 mg/kg) is used for anaesthesia with suxamethonium (0.5-1.0mg/kg) for muscle relaxation.

Interventions: intervention 1: ECT Mecta 5000M intervention 2: Methohexitone intervention 3: Suxamethonium
Intervention descriptions: intervention 1: ECT is administered twice weekly with hand-held electrodes using the Mecta 5000M device following a standard stimulus dosing protocol. Seizure duration is measured by EEG monitoring. Methohexitone (0.75-1.0 mg/kg) is used for anaesthesia with suxamethonium (0.5-1.0 mg/kg) as muscle relaxant. Seizure threshold (ST) is established by a method of limits at the first session and subsequent treatments will be given at 1.5 x ST for BT ECT and 6.0 x ST for RUL ECT. To reflect routine clinical practice, number of ECT treatments is determined by referring physicians who will be blind to randomisation. The treatment period varies between patients to allow up to 12 administrations of ECT, i.e. up to 6 weeks. intervention 2: Methohexitone (0.75-1.0 mg/kg) is used for anaesthesia along with suxamethonium (0.5-1.0 mg/kg)for muscle relaxation. Anesthesia is the same for both arms of the trial. intervention 3: Suxamethonium (0.5-1.0 mg/kg)is used for muscle relaxation along with Methohexitone (0.75-1.0 mg/kg) for anaesthesia. Anesthesia is the same for both arms of the trial.

Protocol document: