Table 3.
Paired t-test results and effect sizes (Cohen’s d) for continuous measures of depression and suicidal ideation, relative to baseline, within the ketamine-treated sample (n = 16).
| Measure | Baseline (n = 16) | Day 1 | Day 1 Statistics | Day 5 | Day 5 Statistics | Day 12 | Day 12 Statistics | Month 1 | Month 1 Statistics | Month 3 | Month 3 Statistics | Month 6 | Month 6 Statistics |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| MADRS total | 37.75 (6.2) | 16.75 (9.71) |
n = 16, t15
= 11.3, p < 0.001, d = 2.6 [1.6,3.4] |
17.53 (9.28) |
n = 15, t14
= 8.7, p < 0.001, d = 2.5 [1.5,3.4] |
16.20 (11.91) |
n = 10, t9
= 5.5, p < 0.001, d = 2.4 [1.2,3.4] |
16.22 (11.72) |
n = 9, t8
= 6.6, p < 0.001, d = 2.3 [1.0,3.3] |
14.09 (10.90) |
n = 11, t10
= 8.8, p < 0.001, d = 2.8 [1.5,3.8] |
15.67 (11.68) |
n = 12, t11
= 7.0, p < 0.001, d = 2.4 [1.2,3.3] |
| MADRS-SI | 5.94 (0.25) | 0.81 (1.22) |
n = 16, t15
= 17.0, p < 0.001, d = 5.8 [4.1,7.3] |
0.80 (1.32) |
n = 15, t14
= 15.3, p < 0.001, d = 5.4 [3.7,6.8] |
0.50 (1.27) |
n = 10, t9
= 13.7, p < 0.001, d = 6.1 [3.9,7.9] |
1.11 (1.76) |
n = 9, t8
= 8.3, p < 0.001, d = 3.9 [2.2,5.3] |
1.18 (1.83) |
n = 11, t10
= 8.7, p < 0.001, d = 3.7 [2.2,4.9] |
1.08 (1.68) |
n = 12, t11
= 10.2, p < 0.001, d = 4.0 [2.5,5.3] |
| CSSRS-SI | 4.94 (0.25) | 0.38 (0.72) |
n = 16, t15= 20.5, p < 0.001, d = 8.5 [6.1,10.4] |
0.47 (0.99) |
n = 15, t14
= 15.4, p < 0.001, d = 6.2 [4.3,7.7] |
0.30 (0.95) |
n = 10, t9
= 15.7, p < 0.001, d = 7.0 [4.5,9.0] |
0.78 (1.39) |
n = 9, t8
= 9.1, p < 0.001, d = 4.3 [2.5,5.7] |
1.36 (1.96) |
n = 11, t10
= 6.0, p < 0.001, d = 2.4 [1.3,3.5] |
0.92 (1.62) |
n = 12, t11
= 8.7, p < 0.001, d = 3.6 [2.2,4.7] |
| ASIQ | 91.93 (32.29) | 38.20 (30.00) |
n = 15, t14
= 6.9, p < 0.001, d = 1.7 [0.9,2.5] |
23.07 (8.46) |
n = 14, t13
= 8.2, p < 0.001, d = 2.8 [1.7,3.8] |
27.17 (27.17) |
n = 12, t11
= 5.9, p < 0.001, d = 2.0 [0.9,2.8] |
36.90 (38.43) |
n = 10, t9
= 4.8, p = 0.001, d = 1.6 [0.5,2.5] |
35.10 (37.79) |
n = 10, t9= 4.8, p = 0.001, d = 1.7 [0.6,2.6] |
43.00 (49.86) |
n = 7, t6
= 4.1, p = 0.006, d = 1.0 [−0.2,2.1] ¥ |
| SSI | 29.29 (1.50) | 3.00 (6.27) |
n = 7, t6
= 9.6, p < 0.001, d = 5.8 [3.1,7.6] |
4.86 (8.25) |
n = 7, t6
= 7.7, p < 0.001, d = 4.1 [2.1,5.6] |
4.50 (9.00) |
n = 4, t3
= 5.1, p = 0.014, d = 3.8 [1.2,5.4] |
6.75 (7.23) |
n = 4, t3
= 6.9, p = 0.006, d = 4.3 [1.4,6.0] |
6.38 (8.70) |
n = 8, t7
= 7.3, p < 0.001, d = 3.6 [1.9,5.0] |
7.50 (10.56) |
n = 10, t9
= 6.6, p < 0.001, d = 2.9 [1.6,4.1] |
| QIDS-SR | 15.9 (5.1) |
11.9 (10.6) |
n = 14, t13
= 2.8, p = 0.015, d = 0.76 [−0.03,1.5] ¥ |
8.15 (4.76) |
n = 13, t12
= 4.3, p < 0.001, d = 1.49 [0.6,2.3] |
7.55 (6.2) |
n = 11, t10
= 4.1, p = 0.002, d = 1.47 [0.5,2.3] |
9.00 (5.68) |
n = 9, t8
= 3.2, p = 0.013, d = 1.20 [0.2,2.1] |
11.56 (6.40) |
n = 9, t8
= 2.2, p = 0.06, d = 0.70 [−0.3,1.6] |
12.14 (3.74) |
n = 7, t6
= 1.19, p = 0.28, d = 0.48 [−0.6,1.5] |
Note: values presented as mean (SD). Paired t-tests compared each post-infusion timepoint to baseline values among the subset of participants who provided data for each measure/timepoint. Cohen’s d effect size was calculated as the standardized mean difference (unadjusted for paired comparisons) with 95% confidence interval [,] for Cohen’s d. Variable n’s for specific measures, as listed in the ‘Day/Month X Statistics’ column, are due to partial-visit completion due to time constraints or participant non-compliance. MADRS = Montgomery–Asberg Depression Rating Scale; SI = suicidal ideation; CSSRS = Columbia Suicide Severity Rating Scale; ASIQ = Adult Suicide Ideation Questionnaire; SSI = Scale for Suicide Ideation; QIDS-SR = Quick Inventory of Depressive Symptoms—Self-Report. The ¥ 95% CI crosses 0 because a conservative equation for Cohen’s d was used which (unlike the corresponding paired t-test) does not adjust for paired comparisons.