Table 1.
Demographics and Clinical Characteristics of the Participants at Baseline*
| Characteristic | Ketamine (N=20) | Placebo (N=20) | Overall (N=40) |
|---|---|---|---|
| Demographic characteristics | |||
| Age — yr | 50.5±12 | 51.9±18.9 | 51.2±15.7 |
| Female sex — no. (%) | 12 (60) | 16 (80) | 28 (70) |
| Male sex — no. (%) | 8 (40) | 4(20) | 12 (30) |
| Race — no. (%)† | |||
| White | 13 (65) | 13 (65) | 26 (65) |
| Black | 2 (10) | 2 (10) | 4 (10) |
| Asian | 0 (0) | 2 (10) | 2 (5) |
| Native Hawaiian or other Pacific Islander | 0 (0) | 1 (5) | 1 (2.5) |
| More than one race | 2 (10) | 0 (0) | 2 (5) |
| Unknown or not reported | 3 (15) | 2 (10) | 5 (12.5) |
| Ethnicity — no. (%)† | |||
| Hispanic | 2 (10) | 2 (10) | 4 (10) |
| Non-Hispanic | 18 (90) | 17 (85) | 35 (87.5) |
| Unknown or not reported | 0 (0) | 1 (5) | 1 (2.5) |
| Married or life partnered — no. (%) | 9 (45) | 9 (45) | 18 (45) |
| Employed — no. (%) | 13 (65) | 12 (60) | 25 (62.5) |
| Never smoked — no. (%) | 14 (70) | 12 (60) | 26 (65) |
| Body mass index — kg/m2 | 29.9±5 | 29.5±4.4 | 29.7±4.7 |
| Previous ketamine exposure — no. (%) | |||
| None or did not know | 15 (75) | 19 (95) | 34 (85) |
| Received in a medical setting | 5 (25) | 1 (5) | 6 (15) |
| Used recreationally | 0 (0) | 0 (0) | 0 (0) |
| Psychiatric history | |||
| Age at first MDD onset — yr | 31.0±14.3 | 21.8±15.0 | 26.5±15.2 |
| Duration of current MDD episode — months | |||
| Mean | 80.1 | 43.7 | 61.9 |
| Median | 38 | 17 | 24 |
| Duration of current MDD episode — no. (%) | |||
| Acute (≤12 months) | 6 (30) | 10 (50) | 16 (40) |
| Subacute (13–24 months) | 1 (5) | 7 (35) | 8 (20) |
| Chronic (>24 months) | 13 (65) | 3 (15) | 16 (40) |
| Recurrent MDD — no. (%) | 11 (55) | 16 (80) | 27 (67.5) |
| Number of antidepressants trialed — no. (%) | |||
| 1–2 | 9 (45) | 7 (35) | 16 (40) |
| 3–4 | 4 (20) | 9 (45) | 13 (32.5) |
| 5–6 | 6 (30) | 2 (10) | 8 (20) |
| 7–10 | 0 (0) | 0 (0) | 0 (0) |
| >10 | 1 (5) | 0 (0) | 1 (2.5) |
| Antidepressant augmentation trialed — no. (%) | 3 (15) | 7 (35) | 10 (25) |
| Electroconvulsant therapy trialed — no. (%) | 0 (0) | 0 (0) | 0 (0) |
| Maudsley Staging Method score | 8.3±2.3 | 7.5±1.7 | 7.9±2 |
| Maudsley Staging Method resistance category — no. (%) | |||
| Mild (<7) | 4 (20) | 5 (25) | 9 (22.5) |
| Moderate (≥7 and <11) | 13 (65) | 14 (70) | 27 (67.5) |
| Severe (≥11) | 3 (15) | 1 (5) | 4 (10) |
| Depression scores | |||
| PHQ-8 total score‡ | 15.8±3.6 | 15.8±3.8 | 15.8±3.7 |
| MADRS total score§ | 27.7±7.8 | 30.6±6.3 | 29.1±7.1 |
| HADS¶ | |||
| Total score | 24.6±6.0 | 24.7±5.7 | 24.6±5.8 |
| Depression subscore | 12.0±3.2 | 10.5±3.6 | 11.2±3.5 |
| Anxiety subscore | 12.6±4.4 | 14.2±3.3 | 13.4±3.9 |
Plus–minus values represent means±SD. Participants were randomized to a single intravenous dose of either ketamine or saline, given during surgical anesthesia. Percentages may not total 100 due to rounding. MDD denotes major depressive disorder.
Race and ethnicity were reported by the participants.
Total scores on the 8-item Patient Health Questionnaire (PHQ-8) range from 0 to 27, with higher scores indicating greater severity of depression.
Total scores on the Montgomery–Åsberg Depression Rating Scale (MADRS) range from 0 to 60, with higher scores indicating greater severity of depression.
Total scores on the Hospital Anxiety and Depression Scale (HADS) range from 0 to 42, with higher scores indicating greater severity of anxiety and depression; subscales range from 0 to 21.
Missing data: Ethnicity for 1 participant in the placebo group; marital status for 2 participants in the ketamine group and 1 participant in the placebo group; age of first MDD onset for 1 participant in the placebo group; recurrent MDD type for 2 participants in the ketamine group; number of antidepressants trialed for 2 participants in the placebo group.