Tiger 2020.

Study characteristics
Methods	Randomised, double‐blind, placebo‐controlled trial
Participants	Diagnosis: major depressive episode according to M.I.N.I., with MADRS ≥ 20 N: 30 Age: ketamine group M = 39.2 (SD = 11.7); placebo group M = 37.1 (SD = 11.1) Sex: ketamine group 40% female; placebo group 60% female Baseline depression severity: ketamine group MADRS M = 26.3 (SD = 6.58); placebo group MADRS M = 30.8 (SD = 4.92)
Interventions	Patients were randomised to receive either 0.5 mg/kg racemic ketamine diluted in 100 mL isotonic NaCl solution, given as an intravenous infusion over 40 minutes. Placebo treatment was an isotonic NaCl solution only. Concomitant medication: ongoing pharmacological treatment was washed out for a time corresponding to at least five half‐lives of each drug prior to beginning study treatment.
Outcomes	MADRS Response Adverse events (obtained from author) PET
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Randomization was performed with sealed opaque envelopes, each containing one of the study treatment allocations. Before the start of treatment, a nurse not involved in patient assessments opened a new envelope, assigning the patient to the randomized treatment allocation".
Allocation concealment (selection bias)	Low risk	Quote:"Randomization was performed with sealed opaque envelopes, each containing one of the study treatment allocations. Before the start of treatment, a nurse not involved in patient assessments opened a new envelope, assigning the patient to the randomized treatment allocation".
Blinding of participants and personnel (performance bias) All outcomes	High risk	Patient blinding not effective: quote:"Patients who received active treatment in the double blinded phase were all convinced they received ketamine, while four out of ten placebo treated patients thought that they were actually given the active treatment". Unknown whether personnel blinding was effective.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Patients and personnel blinded, however this was not effective for patients, unclear for personnel.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Withdrawals reported in article: quote:"No patient was discontinued after randomization".
Selective reporting (reporting bias)	Unclear risk	No protocol accesible.
Other bias	Low risk	None identified.