Effectiveness rates based on
electrode placement and electricity amount
Placement Dosage Effectiveness
Unilateral Low dose* 17 %
Unilateral Suprathreshold** 43 %
Bilateral Low Dose 65 %
Bilateral Suprathreshold 63 %
* low dose: just enough electricity to produce convulsion
** suprathreshold: 2.5 times the amount electricity needed to produce convulsion


Effects of stimulus intensity and electrode placement on the efficacy and cognitive effects of electroconvulsive therapy
Authors: Sackeim HA, et al.
N Engl J Med -- 1993 Mar 25;328(12):882-3

Abstract:
BACKGROUND. The efficacy of electroconvulsive therapy in major depression is established, but the importance of the electrical dosage and electrode placement in relation to efficacy and side effects is uncertain.

METHODS. In a double- blind study, we randomly assigned 96 depressed patients to receive right unilateral or bilateral electroconvulsive therapy at either a low electrical dose (just above the seizure threshold) or a high dose (2.5 times the threshold). Symptoms of depression and cognitive functioning were assessed before, during, immediately after, and two months after therapy. Patients who responded to treatment were followed for one year to assess the rate of relapse.

RESULTS. The response rate for low-dose unilateral electroconvulsive therapy was 17 percent, as compared with 43 percent for high-dose unilateral therapy (P = 0.054), 65 percent for low-dose bilateral therapy (P = 0.001), and 63 percent for high-dose bilateral therapy (P = 0.001). Regardless of electrode placement, high dosage resulted in more rapid improvement (P therapy (59 percent) relapsed, and there were no differences between treatment groups.

CONCLUSIONS. Increasing the electrical dosage increases the efficacy of right unilateral electroconvulsive therapy, although not to the level of bilateral therapy. High electrical dosage is associated with a more rapid response, and unilateral treatment is associated with less severe cognitive side effects after treatment.

Electroconvulsive therapy in the treatment-resistant patient.
Authors: Devanand DP, Sackeim HA, Prudic J
Psychiatr Clin North Am
1991 Dec

Abstract:
In medication-resistant patients with major depressive disorder, the response rate with bilateral electroconvulsive therapy (ECT) drops to 50% from the expected range of 80% to 90%. Relapse rates following ECT are high in medication- resistant depressed patients and are clustered in the first 4 months following clinical response. Medication resistance during the index episode predicts a high rate of relapse, whereas those patients who have not received an adequate medication trial prior to ECT are less likely to relapse. If a patient who fails an antidepressant trial then responds to a course of ECT, alternative pharmacologic strategies or maintenance ECT should be considered to decrease the likelihood of relapse. Patients who do not respond to a traditional course of bilateral ECT may respond subsequently to longer courses of bilateral ECT at markedly suprathreshold stimulus intensity, or may respond to a different class of antidepressant medication from that which they failed previously.


Patient selection and remission rates with the current practice of electroconvulsive therapy in Germany
Authors: Kornhuber J, Weller M
Convuls Ther 1995 Jun;11(2):104-109 /TD>

Disorder TreatedEffectiveness of ECT
Unipolar
31.9%
Bipolar
38.3%

The current practice of German psychiatric hospitals restricts electroconvulsive therapy (ECT) to patients with profound disability and failure to respond to pharmacotherapy. We studied clinical features and seizure parameters in 63 patients who received ECT in a 3-year period at a German university hospital. Patients with unipolar and bipolar disorder (depressed) (n = 47) showed a complete or partial recovery as assessed 2 weeks after completion of the ECT course in 31.9 and 38.3%, respectively. Multiple linear regression analysis performed on several clinical and ECT seizure parameters failed to identify strong outcome predictors in our selected sample of patients. Most patients who eventually responded did so early in the course of ECT, while there was little improvement when 10 ECT treatments were given. Our report highlights the efficacy of ECT in the management of severe psychiatric disorders even in a highly selected sample of patients previously found to be resistant to alternative modes of psychiatric treatment.


The impact of medication resistance and continuation pharmacotherapy on relapse following response to electroconvulsive therapy in major depression.
Authors: Sackeim HA, Prudic J, Devanand DP, Decina P, Kerr B, Malitz S
J Clin Psychopharmacol 1990 Apr;10(2):96-104

After clinical response to electroconvulsive therapy (ECT), 58 patients with major depressive disorder were followed for 1 year or until relapse. The rate of relapse was substantially higher in patients who had failed adequate antidepressant medication trials prior to ECT than in patients not determined to be medication resistant. Adequacy of post-ECT pharmacotherapy was only marginally related to likelihood of relapse. The subgroup of patients who appeared to benefit from adequate post-ECT pharmacotherapy were those who did not receive an adequate medication trial prior to ECT. The findings call into question the common practice of administering as continuation pharmacotherapy following ECT the same class of medications that patients had failed with during the acute episode prior to ECT. The findings also indicate that resistance to antidepressant medication is a strong predictor of relapse following response to ECT.

Electroconvulsive therapy in the treatment-resistant patient.
Authors: Devanand DP, Sackeim HA, Prudic J Psychiatr Clin North Am 1991 Dec;14(4):905-923

In medication-resistant patients with major depressive disorder, the response rate with bilateral electroconvulsive therapy (ECT) drops to 50% from the expected range of 80% to 90%.

Relapse rates following ECT are high in medication-resistant depressed patients and are clustered in the first 4 months following clinical response. Medication resistance during the index episode predicts a high rate of relapse, whereas those patients who have not received an adequate medication trial prior to ECT are less likely to relapse. If a patient who fails an antidepressant trial then responds to a course of ECT, alternative pharmacologic strategies or maintenance ECT should be considered to decrease the likelihood of relapse. Patients who do not respond to a traditional course of bilateral ECT may respond subsequently to longer courses of bilateral ECT at markedly suprathreshold stimulus intensity, or may respond to a different class of antidepressant medication from that which they failed previously.