Ketamine As an Adjunctive Therapy for Major Depression (2)

The MADRS is a validated, 10-item, observer-rated scale that measures the symptoms and severity of depression. The primary outcome measure will be the change from baseline in the MADRS score to 24 hours after the final infusion.

MADRS will be completed at screening (prior to randomisation), before and after all infusion sessions (at the following timepoints: -40 (±20) mins before the infusion begins; +60 (±10) mins and +120 (±10) mins after the infusion begins; +24 (±1) hours after the infusion ends) and at the 6, 12 and 24 weeks follow-up time points. Sleep and appetite scores will be carried over from -40 minutes to +60 minutes, +120 minutes, and 24 hours after each infusion.

Response to treatment is defined as a ≥50% improvement from baseline MADRS score. Remission is defined as achieving a MADRS score ≤10. For those deemed to be treatment remitters, relapse at follow-up time points is defined as a MADRS score of ≥18.

The CADSS will measure dissociative symptoms, as a possible subjective side effect of either ketamine or midazolam. The CADSS consists of 23 items and scores for each item range from 0 to 4. The CADSS measures dissociative symptoms in the following domains: identity, proprioception, time perception, colour and depth perception, and other modalities. The maximum score is 92, with higher scores indicating more dissociative symptoms.

The CADSS will be completed three times at each infusion session: before (-30 (±10) mins before the infusion begins), during (+30 (±5) mins after the infusion begins) and after (+60 (±10) mins after the infusion begins, i.e. 20 (±10) mins after the infusion ends).

The positive symptoms subscale of the BPRS will be used to measure psychotomimetic effects of either ketamine or midazolam. This 4-item positive symptoms subscale measures suspiciousness, hallucinations, unusual thought content, and conceptual disorganisation. Each item is scored between 0 and 7. The maximum score is 28, with higher scores indicating more severe psychotic symptom.

Participants will complete the BPRS three times at each infusion session: before (-30 (±10) mins before the infusion begins), during (+30 (±5) mins after the infusion begins) and after (+60 (±10) mins after the infusion begins, i.e. 20 (±10) mins after the infusion ends).

The YMRS is an observer-rated assessment tool for severity of mania and hypomania. The single mood item of the YMRS, rated from 0 to 4 (representing a range from normal mood to frank euphoria), will be used to assess for possible mood elevation during the infusion sessions. Higher scores reflect more elevated mood.

Participants will have the YMRS performed three times at each infusion session: before (-30 (±10) mins before the infusion begins), during (+30 (±5) mins after the infusion begins) and after (+60 (±10) mins after the infusion begins, i.e. 20 (±10) mins after the infusion ends).

The OAA/S-R is an observer-rated assessment that will be used to measure levels of sedation experienced by participants during either ketamine or midazolam infusion. The OAA/S-R ranges in score from 1 to 5, where 1 denotes deep sleep (i.e. no response to mild prodding or shaking) and 5 denotes fully alert.

The OAA/S-R will be completed three times at each infusion session: before (-30 (±10) mins before the infusion begins), during (+30 (±5) mins after the infusion begins) and after (+60 (±10) mins after the infusion begins, i.e. 20 (±10) mins after the infusion ends).

The PWC-20 will be used to assess for potential withdrawal symptoms during and after completion of the allocated course of ketamine/midazolam infusions. The PWC-20 is a brief checklist and each item is rated from 0 (not present) to 3 (severe). PWC-20 scores range from 0 to 60, with higher scores indicating more withdrawal symptoms with greater severity.

The PWC-20 will be completed at screening (prior to randomisation), 24 (±1) hours after the end of the fourth and final infusions, and the 6- and 12-week follow-up timepoints.

The QIDS-SR is a validated, self-report measure of depressive symptoms. The QIDS-SR consists of 16 items, with each item rated on a scale from 0 to 3. Total scores range from 0 to 48, with higher scores reflecting greater burden of depressive symptoms.

The QIDS-SR will be completed at screening (prior to randomisation), before and after all infusion sessions (at the following timepoints: -40 (±20) mins before the infusion begins; +60 (±10) mins and +120 (±10) mins after the infusion begins; +24 (±1) hours after the infusion ends) and at the 6, 12 and 24 weeks follow-up time points. Sleep and appetite items 1,2,3,4,6,7,8 & 9 on the QIDS-SR will be carried over from -40 minutes before each infusion to +60 minutes, +120 minutes & 24 hours after each infusion in line with the methodology of previous literature.

The PRISE is a 9-item, self-report measure that will document general adverse events experienced by patients during each infusion, by identifying and evaluating the tolerability of each adverse event. The PRISE assesses adverse events in the following symptom domains; Gastrointestinal, Heart, Skin, Nervous System, Eyes/Ears, Genital/Urinary, Sleep, Sexual Functioning, and Other. Each domain has multiple symptoms which can be endorsed. For each domain the patient rate whether or not the symptoms are tolerable or distressing.

The PRISE will be completed at screening (prior to randomisation), after all infusion sessions (+120 (±10) mins after the infusion begins), and at the 6, 12 and 24 weeks follow-up time points.

The MoCA is a rapid screening instrument for mild cognitive dysfunction. It assesses the following cognitive domains: attention and concentration, executive functions, memory, language, conceptual thinking, calculations, and orientation. The maximum score is 30, with higher scores indicating better cognition.

The MoCA will be completed at screening (prior to randomisation), at +120 (±10) mins after the infusion begins during the first and final infusion sessions, and at the 12 and 24 weeks follow-up time points.

Health-related quality-of-life will be measured using the EQ-5D-5L. The EQ-5D-5L consists of the EQ-5D descriptive system, and the EQ visual analogue scale (EQ VAS).

The EQ-5D descriptive system includes the following five dimensions that assess an individual's self-rated health status: mobility, self-care, usual activities, pain/discomfort and anxiety/depression. Each dimension is rated on a 5-point Likert scale. The digits related to each response to the five dimensions are combined into a 5-digit number, which describes the patient's health state.

The EQ VAS includes a vertical visual analogue as a quantitative measure of subjectively rated health, with endpoints labelled as 'Best imaginable health status' and 'Worst imaginable health status'.

The EQ-5D-5L will be administered at screening (prior to randomisation) and at the 6-, 12- and 24-week follow up time periods.

The CSRI will calculate healthcare costs using the following data: sociodemographic information, usual living situation, employment status and income levels and the care services and supports used by participants. Currently prescribed medicines will also be recorded.

Healthcare costs will be estimated using the CSRI at baseline and at the 6-, 12- and 24-week follow-up timepoints.

AEs and SAEs will be reviewed at every visit. All AEs and SAEs will be reported and followed up until resolved or until final visit.

All medications taken one month prior to participant screening will be recorded. At all other visits, concomitant medication taken since last visit will be documented. Adherence to prohibited/contraindicated medication requirements will be assessed and documented at each infusion visit.