. 2019 Nov 29;19:375. doi: 10.1186/s12888-019-2359-1

Table 1.

Inclusion and exclusion criteria

Subject eligibility
Inclusion criteria	1. Age 18 to 80 years; 2. Current major depressive episode according to the DSM-5, ascertained by the MINI; 3. Depression at least moderately severe, defined by a score > 18 on the HDRS₁₇; 4. TRD, defined as insufficient lifetime response to 3 or more different classes of antidepressant drugs, given for at least 4 weeks and in an adequate dose; 5. Stable dose of current antidepressant drug for at least 4 weeks prior to study initiation; 6. Good understanding of spoken and written Dutch.
Exclusion criteria	1. Meet DSM-5 criteria for current major depressive episode with psychotic features, bipolar disorder, past or current psychotic disorder, past or current moderate or severe substance dependence, or personality disorder as a primary diagnosis; 2. Recent (within the last 4 weeks) or current use of non-prescribed psychoactive compounds; 3. Recent (within the last 4 weeks) or current use of benzodiazepines in excess of 2 mg lorazepam or equivalent per day; 4. Current electroshock therapy; 5. Active suicidal intent, defined by a score > 2 on item 3 of the HDRS₁₇; 6. Pregnancy or lactation; 7. A relevant somatic disorder, ascertained by physical examination, electrocardiogram, and blood tests; 8. Use of medication that ketamine interacts with on a major level according to the Drug Interactions Checker [34], including monoamine oxidase inhibitors.

Subject eligibility

Inclusion criteria

1. Age 18 to 80 years;

2. Current major depressive episode according to the DSM-5, ascertained by the MINI;

3. Depression at least moderately severe, defined by a score > 18 on the HDRS₁₇;

4. TRD, defined as insufficient lifetime response to 3 or more different classes of antidepressant drugs, given for at least 4 weeks and in an adequate dose;

5. Stable dose of current antidepressant drug for at least 4 weeks prior to study initiation;

6. Good understanding of spoken and written Dutch.

Exclusion criteria

1. Meet DSM-5 criteria for current major depressive episode with psychotic features, bipolar disorder, past or current psychotic disorder, past or current moderate or severe substance dependence, or personality disorder as a primary diagnosis;

2. Recent (within the last 4 weeks) or current use of non-prescribed psychoactive compounds;

3. Recent (within the last 4 weeks) or current use of benzodiazepines in excess of 2 mg lorazepam or equivalent per day;

4. Current electroshock therapy;

5. Active suicidal intent, defined by a score > 2 on item 3 of the HDRS₁₇;

6. Pregnancy or lactation;

7. A relevant somatic disorder, ascertained by physical examination, electrocardiogram, and blood tests;

8. Use of medication that ketamine interacts with on a major level according to the Drug Interactions Checker [34], including monoamine oxidase inhibitors.

DSM-5 5th edition of the Diagnostic and Statistical Manual of Mental Disorders [35], HDRS₁₇ 17-item Hamilton Depression Rating Scale [36, 37], MINI Mini International Neuropsychiatry Interview [38], TRD Treatment-resistant depression