Table 2.
Univariate associations of demographic, clinical, Fitbit, and daily diary variables with depression and suicidal ideation at Q1 follow-up
| Depression Q1 | Suicidal Ideation Q1 | |||||
|---|---|---|---|---|---|---|
| No (82.4%) Mean(SD) | Yes (17.6%) Mean(SD) | Test statistic t(df) or χ2(df) | No (92.3%) Mean(SD) | Yes (7.7%) Mean(SD) | Test statistic t(df) or χ2(df) | |
|
| ||||||
| Sex (% Female) | 55.7% | 61.6% | χ2(1) = 5.75* | 57.1% | 53.5% | χ2(1) = 1.06 |
| R/E (% White) | 58.4% | 58.0% | χ2(5) = 9.24 | 58.7% | 55.3% | χ2(5) = 5.38 |
| Pre SI (% Yes) | 1.5% | 10.1% | χ2(1) = 100.40*** | 1.5% | 21.8% | χ2(1) = 278.00*** |
| Age | 27.48 (2.9) | 27.64 (3.0) | t(2832) = 1.10 | 27.50 (2.9) | 27.78 (2.7) | t(2805) = 1.38 |
| Pre PHQ-9 | 2.16 (2.3) | 4.96 (3.8) | t(579.4) = 15.73*** | 2.45 (2.6) | 5.00 (4.1) | t(231.5) = 9.02*** |
| Sleep features | ||||||
| Mean | 6.36 (1.1) | 6.28 (1.3) | t(526.9) = 1.18 | 6.34 (1.1) | 6.40 (1.0) | t(2328) = 0.66 |
| Variability (SD) | 1.55 (0.6) | 1.65 (0.6) | t(2295) = 3.10** | 1.56 (0.6) | 1.63 (0.6) | t(2277) = 1.55 |
| Slope | −0.358 (17.1) | −0.354 (19.9) | t(2295) = 0.01 | −0.269 (17.7) | −0.545 (12.5) | t(2277) = 0.21 |
| Completion % | 54.62 (38.3) | 51.48 (38.6) | t(2839) = 1.67 | 53.94 (38.3) | 57.45 (37.7) | t(2812) = 1.30 |
| Step features | ||||||
| Mean | 8,623 (2,689) | 8,373 (2,696) | t(2461) = 1.75 | 8,585 (2,670) | 8,616 (2,963) | t(2438) = 0.15 |
| Variability (SD) | 3,662 (1,259) | 3,552 (1,126) | t(2444) = 1.66 | 3,642 (1,228) | 3,641 (1,304) | t(2421) = 0.01 |
| Slope | 34.72 (507.8) | 35.36 (135.6) | t(2444) = 0.02 | 36.87 (552.8) | 28.31 (135.6) | t(2421) = 0.21 |
| Completion % | 68.68 (37.5) | 66.50 (38.4) | t(2839) = 1.72 | 68.93 (37.8) | 72.71 (35.9) | t(257.6) = 1.49 |
| Mood features | ||||||
| Mean | 7.42 (1.0) | 6.44 (1.3) | t(632.1) = 15.51*** | 7.33 (1.1) | 6.27 (1.4) | t(237.8) = 10.66*** |
| Variability (SD) | 1.00 (0.4) | 1.27 (0.5) | t(651.0) = 10.56*** | 1.03 (0.5) | 1.28 (0.5) | t(241.4) = 6.56*** |
| Slope | 0.0015 (0.03) | 0.0029(0.04) | t(623.6) = 0.77 | 0.0017 (0.04) | 0.0033(0.05) | t(2752) = 0.61 |
| Completion % | 51.08 (26.1) | 47.46 (26.9) | t(2839) = 2.80** | 50.50 (26.2) | 50.35 (27.0) | t(2812) = 0.08 |
Note.
*
p <.05
**
p <.01
***
p < .001. Sleep variables were scaled to hours. Mood was scored from 1–10, with lower scores indicating worse mood. Depression as an outcome was indicated by a score of 10 or higher on the PHQ-9. R/E = Race/Ethnicity. Pre = Pre-internship. Q1 = Quarter 1 follow-up assessment. SI = Suicidal Ideation. PHQ-9 = Patient Health Questionnaire-9 score. SD = Standard deviation.