Table 3.
Adjusted Mean Difference in Change in PHQ-9 Score at 2-Year Follow-Up Comparing Omega-3s and Placebo Groups by Risk Group of Indicated and Selective Preventiona
| Omega-3s vs Placebo | |||
|---|---|---|---|
| Risk Group | Eligible Participants, n | Mean Difference (95% CI)b | P-Interactionc |
| Subthreshold depression | .23 | ||
| Yesd | 80 | 0.84 (−0.36 to 2.03) | |
| No | 640 | 0.11 (−0.08 to 0.30) | |
| 1+ High-risk factors for LLD | .05 | ||
| Yese | 438 | 0.35 (0.04 to 0.66) | |
| No | 282 | −0.05 (−0.31 to 0.21) | |
For this coprimary outcome, P < .025 was considered as threshold for statistical significance. The prespecified MCID (minimally clinically important difference) in PHQ-9 score was 0.5 points.
Results are from repeated measures model; all participants contributed to the repeated measure analysis at one and/or both time points. Models were controlled for age, sex, and vitamin D3 randomization group.
P-interaction is from the test of the prevention category × treatment × time interaction term in the model.
Indicated prevention targeted participants with subthreshold depression, but who did not meet DSM-IV criteria for current major depressive disorder or dysthymia, at baseline.
Selective prevention targeted participants with ≥ 1 high-risk factor for LLD at baseline; see details in Supplementary Appendix 1 (under E. Approach for selective prevention).
Abbreviations: LLD = late-life depression, PHQ = Patient Health Questionnaire-9.