Table 1. Samples clinical characteristics.
| Major depression | Healthy control | P | |
|---|---|---|---|
| Primary sample | |||
| n | 20 | 19 | |
| Age, years | 29.55 (6.59) | 30.05 (6.71) | 0.81 |
| Male/female | 2, 18 | 2, 18 | 1 |
| MÅDRS | 27.25 (4.24) | 0.95 (1.39) | <0.001 |
| HDRS anxiety subscale | 4.95 (2.48) | 0.21 (0.42) | <0.001 |
| RRS | 56.00 (10.23) | 29.67 (6.44) | <0.001 |
| Time since illness onset, years | 6.35 (6.41) | — | — |
| Comorbid diagnoses | None | — | — |
| Hospitalizations | 0 | — | — |
| Number of episodes | 1.5 (1.25) | — | — |
| Validation sample | |||
| n | 19 | 19 | |
| Age, years | 32.34 (10.62) | 31.91 (10.30) | 0.90 |
| Male/female | 7, 12 | 6, 13a | 0.73 |
| MÅDRS | 30.74 (7.31) | 1.37 (1.86) | <0.001 |
| HDRS anxiety subscale | 7.16 (1.30) | 0.31 (0.58) | <0.001 |
| RRS | 66.47 (8.22) | 30.63 (6.83) | <0.001 |
| Time since illness onset, years | 13.50 (8.26) | — | — |
| Comorbid diagnoses | N=12 (9 GAD, 5 SAD, 4 OCD, 2 PD, 2 PTSD, 1 historic substance abuse) | — | — |
| Hospitalizations | 4 | — | — |
| Number of episodes | 4 (2.5) | — | — |
Abbreviations: GAD, generalized anxiety disorder; HDRS, Hamilton Depression Rating Scale (17 item); MÅDRS, Montgomery-Åsberg Depression Rating Scale; OCD, obsessive compulsive disorder; PD, panic disorder; PTSD, post-traumatic stress disorder; RRS, Ruminative Response Scale; SAD, social anxiety disorder.
Demographics for the validation sample represent the 19 healthy controls included in the final analysis. The samples did not differ on depression severity (t(37)=−1.83, P=0.07). The validation sample had a significantly higher anxiety score (t(37)=3.45, P=0.001), time since illness onset (t(37)=2.62, P=0.01) and RRS score (t(37)=3.51, P=0.001) than the primary sample.
Values are reported as mean (standard deviations) for all variables except number of episodes where due to skewed data we report median (interquartile range).