Out of 78 forensic psychiatric hospitals in Ger, n = 41 participated in the questionnaire study (response rate 52.6%). Out of these, 36 provided information on the number of detained patients, resulting in a total of 5054. Most common diagnoses were addictive disorders (46.8%) and schizophrenia (41.4%). Five hospitals exclusively reported patients with addictive disorders.

Out of 6 forensic psychiatric hospitals in Sui, n = 4 participated (response rate 66.7%), reporting a total of 175 detained patients. Schizophrenia was the most common diagnosis by far (83.6%).

On the numeric scale from 0 to 10 (0 = not effective at all, 10 = highly effective), the estimated mean effectiveness of ECT for the treatment of depression was 8.00 in Ger (n = 39; SD = 1.56; Med = 8.00) and 8.50 in Sui (n = 4, SD = 0.58; Med = 8.50). For the treatment of schizophrenia, it was rated 6.05 in Ger (n = 39, SD = 1.89; Med = 6.00) and 5.00 in Sui (Sui; n = 3, SD = 2.65; Med = 5.00).

In Ger, the majority of respondents reported to have own experience in the application of ECT in patients with depression (n = 26 out of 40, 65.0%) and schizophrenia (n = 25 out of 40, 62.5%) within their hospital. In Sui, n = 1 out of 4 (25.0%) respondents stated existing ECT experience in the application of ECT in patients with depression, and n = 1 out of 4 (25.0%) in patients with schizophrenia.

The respondents from Ger stated that M = 7.35% (n = 36, SD = 9.12, min = 0, max = 50; Med = 5.00) of the patients within their hospital had an indication for ECT. This resulted in a total number of 360 out of 4903 patients from the 36 hospitals that participated in this study. The general need for ECT in forensic psychiatry (see Fig. 1) was rated M = 6.44 (n = 39, SD = 2.88; Med = 8.00) on the numeric scale (0 = no need, 10 = urgently needed).

Estimated need for ECT in forensic psychiatry, rated by the participating forensic psychiatric hospitals from Germany and Switzerland

For the participating forensic hospitals from Sui, the respondents estimated that M = 7.50% (n = 4, SD = 5.00, min = 5, max = 15; Med = 5.00) of their patients had an indication for ECT, leading to a total number of 13 out of 175. The general need for ECT in forensic psychiatry (see Fig. 1) was rated 6.50 (n = 4; SD = 2.38, Med = 7.50).

For n = 29 out of 41 forensic psychiatric hospitals in Ger (70.7%) and all n = 4 hospitals from Sui it was stated that they have the possibility to offer ECT. For the 12 clinics without ECT, the most common reason why it ECT could not be performed was described as lack of infrastructure (n = 9). Legal obstacles (n = 2) and ethical concerns (n = 1) were mentioned less frequently by the participants.

With regard to ECT in patients without capacity to consent, about half of the respondents from forensic psychiatric clinics with ECT stated that they would consider to treat patients against their will (Ger: n = 15, 51.7%; Sui: n = 2, 50.0%).

For n = 13 forensic psychiatric hospitals in Ger (44.8% of the hospitals with possibility to perform ECT) participants reported at least one treatment with ECT over the last 12 months, with a total of 36 treated patients (min = 1, max = 8).

A total of 2 patients were treated in n = 1 forensic psychiatric hospital in Sui (25.0% of the hospitals with possibility to perform ECT).

The participating forensic psychiatric hospitals in Ger provided demographic and clinical data for n = 29 of the reported 36 patients, the Sui forensic psychiatric hospitals for both reported patients.

As described above, details were provided for n = 31 patients with ECT (Ger and Sui). All except one (ICD-10: F33.2) suffered from schizophrenia (ICD-10: F2x). The most common indication for ECT were treatment resistant psychotic symptoms (GER: n = 25 out of 29, 86.2%; Sui: n = 2 out of 2, 100%). Only one patient in Ger received ECT without consent, none in Sui.

The majority of patients from Ger (n = 16 out of 29, 55.2%) and n = 1 out of 2 patients from Sui (50.0%) achieved a score of “1” or “2” on the CGI-I scale and thus could be identified as responders. In the subgroup of these n = 16 responders, restraints or detention could be reduced in 14 patients (87.5%) consequently. Furthermore, the majority of the patients with ECT in Ger (n = 16 out of 29, 55.2%) and both patients from Switzerland reported temporary side effects, specifically “cognitive decline” (Ger: n = 11 out of 29, 37.9%; Sui: n = 2 out of 2, 100%) and “post-ECT delirium” (Ger: n = 3 out of 29, 10.3%; Sui: no cases). For further details, please see Table 1; Fig. 2.

Reported outcome of the ECT-treated patients in German and Swiss forensic psychiatric hospitals, using the Clinical global impression scale– global improvement (CGI-I)