Table 4.
Binary Mediation Coefficients for Accelerated aging at Y20 (2005–2006) Mediating the Relationship between Social Factors at Y15 (2000–2001) and Stroke after at Y20 (2007–2016): CARDIA, 2000–2016.
| Depression Score (Points, Continuous) |
Racial Discrimination Score (Points, Continuous) |
Socioeconomic Status Score (Points, Continuous) |
||||
|---|---|---|---|---|---|---|
| Binary Mediation Resultsa | Unadjusted (95% CI) | Adjustedb (95% CI) | Unadjusted (95% CI) | Adjustedc (95% CI) | Unadjusted (95% CI) | Adjusted (95% CI) |
| Path a | 0.12 (0.09, 0.16) | 0.03 (-0.001, 0.07) | 0.30 (0.26, 0.34) | 0.28 (0.24, 0.31) | -0.26 (-0.30, 0.22) | -0.09 (-0.13, -0.06) |
| Path b | 0.38 (0.23, 0.53) | 0.33 (0.12, 0.54) | 0.37 (0.22, 0.52) | 0.37 (0.19, 0.56) | 0.40 (0.23, 0.56) | 0.37 (0.15, 0.60) |
| a*b (indirect effect of X on Y) | 0.05 (0.03, 0.07) | 0.01 (0.003, 0.02) | 0.11 (0.07, 0.15) | 0.10 (0.06, 0.15) | -0.10 (-0.14, -0.07) | -0.04 (-0.06, -0.02) |
| Total Effect of X on Y | 0.21 (0.10, 0.31) | 0.15 (-0.01, 0.27) | 0.25 (0.07, 0.41) | 0.25 (0.06, 0.42) | -0.16 (0.02, -0.31) | 0.01 (-0.21, 0.26) |
| Percent total effect mediated (% indirect of total effect) | 22.49% | 7.33% | 46.22% | 40.84% | 68.45% | -485.89%d |
The coefficient for Path a corresponds to the association between the independent variable and the mediator; the coefficient for path b corresponds to the association between the mediator and the outcome; a*b corresponds to the effect of the mediation. 95% CI of a*b is bias-corrected and tests whether different than zero; The total effect of X on Y reports the indirect and direct effect of the independent variable on the outcome; percent total effect mediated is the percentage of the outcome that can be attributed to the mediator.
Path a = pathway from independent variable (depression score, racial discrimination, or SES score) to mediator (accelerated aging); Path b = pathway from mediator (accelerated aging) to outcome (stroke).
Adjusted for sex, chronological age, race, site, smoking status, and mL alcohol per week.
Model with racial discrimination as independent variable not adjusted for race.
Addition of covariates suppressed direct effect resulting in inconsistent mediation.