Table 1.
Descriptive statistics of the study samples of NESDA and DELTA
| NESDA (n = 356) | DELTA‐1st cohort (n = 75) | DELTA‐neuroimaging (n = 43) | |
|---|---|---|---|
| Sociodemographics | |||
| Age, mean (SD) | 42.8 (12.6) | 46.1 (9.05) | 52.3 (7.84) |
| Female, n (%) | 249 (69.9) | 57 (76.0) | 29 (67.4) |
| Education levels | |||
| Low, n (%) | 10 (2.8) | 26 (34.7) | 16 (37.2) |
| Middle, n (%) | 166 (46.6) | 26 (34.7) | 19 (44.2) |
| High, n (%) | 180 (50.6) | 20 (26.7) | 9 (18.6) |
| Lifestyle | |||
| Smoking, yes, n (%) | 146 (41.0) | 15 (20.0) | 8 (18.6) |
| Alcohol (# of glasses), median (p25‐p75) | 3.74 (1.04–8.72) | 2.00 (0.00–8.00) | 4.88 (0.44–12.0) |
| Somatic health | |||
| Waist circumference, median (p25‐p75) | 86.0 (79.0–95.0) | 87.0 (80.0–96.0) | 94.5 (86.0–106.0) |
| Medication or supplement use | |||
| Antidepressant use, yes n (%) | 71 (19.9) | 41 (54.7) | 0 (0.0) |
| Statin use, yes n (%) | 17 (4.8) | 4 (5.3) | 7 (16.3) |
| N‐3 PUFA supplement use, yes (%) | 16 (4.5) | ‐ | 6 (14.0) |
| MDD characteristics | |||
| Residual symptoms on IDS‐SR30, median (p25‐p75) | 9.00 (5.00–11.0) | ‐ | ‐ |
| Residual symptoms on HDRS, median (p25‐p75) | ‐ | 3.00 (1.00–5.00) | 2.00 (1.00–5.00) |
| Time since last MDD episode (months), median (p25‐p75) | 26.0 (11.3–33.8) | 24.0 (6.00–55.0) | |
| Between 1 and 6 months ago, n (%) | 49 (13.8) | ||
| Between 6 months and 12 months ago, n (%) | 26 (7.3) | ||
| More than 12 months ago, n (%) | 213 (59.8) | ||
| Number of previous MDD episodes during lifetime | |||
| Median (p25‐p75) | 1.00 (1.00–3.00) | 5.00 (3.00–10.0) | 3.00 (2.00–5.00) |
| Number of participants with MDD relapse (the event) | 98 (27.5) | 41 (54.7) | 26 (60.5) |
| Cumulative follow‐up time to event/censoring (in months)† | 18 192 | 3145 | 691 |
| Incidence rate (per 100 persons‐months)‡ | 0.54 | 1.30 | 3.76 |
| Follow‐up duration in months, mean (SD) | 63.2 (21.4) | 67.6 (33.7) | 29.6 (1.70) |
| Fatty acids | |||
| DHA, median (p25‐p27)§ | 0.14 (0.11–0.17) | 14.4 (11.9–17.5) | 23.9 (17.1–29.1) |
| EPA, median (p25‐p75)§ | N.A. | 3.10 (2.20–4.30) | 3.80 (2.80–5.50) |
| Total n‐3 PUFA, median (p25‐p75)§ | 0.38 (0.32–0.47) | 27.8 (24.5–32.3) | 41.8 (35.1–50.6) |
| Total n‐6 PUFA, median (p25‐p75)§ | 3.93 (3.43–4.44) | 162.4 (157.4–178.8) | 181.5 (173.8–189.7) |
| n‐3:n‐6 PUFA ratio, median (p25‐p75)§ | 0.10 (0.08–0.11) | 0.15 (0.12–0.17) | 0.22 (0.19–0.25) |
| Chain length index, median (p25‐p75)§ | 17.3 (17.1–17.6) | 18.4 (18.4–18.5) | 18.7 (18.6–18.8) |
| Unsaturation index, median (p25‐p75)§ | 1.23 (1.18–1.26) | 1.33 (1.31–1.35) | 1.44 (1.39–1.45) |
SD, standard deviation; p25‐p27, 25th percentile–75th percentile; MDD, major depressive disorder; N.A., not applicable.
†
Cumulative follow‐up time until event/censoring is the sum of all time until event/censoring for all participants, expressed in months.
‡
Incidence rate: number of participants developing disease/time to event/censoring in months * 100.
§
FA levels in NESDA are expressed in mmol/L and in the DELTA studies in pmol/106 erythrocytes.