Table 3.
Combined Effect of Dichotomized Reserve Indicator (High vs Low) and Genetic Risk of Dementia (Any APOE‐ε4 Carrier vs Noncarrier) Used for the Calculation of Additive Interaction
| Joint Effect | Basic Adjusteda | Multiadjustedb | ||||
|---|---|---|---|---|---|---|
| Cognitive Reserve | APOE‐ε4 | Subjects (cases) | HR (95% CI) | p | HR (95% CI) | p |
| High | No | 1,236 (65) | Reference | Reference | ||
| Low | No | 592 (79) | 1.53 (1.09–2.14) | 0.014 | 1.56 (1.11–2.19) | 0.010 |
| High | Yes | 504 (34) | 1.56 (1.03–2.37) | 0.036 | 1.54 (1.01–2.34) | 0.043 |
| Low | Yes | 224 (54) | 3.30 (2.29–4.74) | <0.001 | 3.25 (2.25–4.69) | <0.001 |
Measures of additive interaction (from the model with multiple confounder adjustment): relative excess risk due to interaction, 1.276, 95% CI = 0.189–2.363; attributable proportion due to interaction, 0.380, 95% CI = 0.123–0.638; synergy index, 2.183, 95% CI = 1.010–4.720.
a
Adjusted for baseline age and sex.
b
Adjusted for baseline age cohorts, sex, smoking, body mass index, heart disease, hypertension, cerebrovascular diseases, and diabetes.
CI = confidence interval; HR = hazard ratio.