Table 3.
Interactions between aerobic capacity and BMI among 18-year-old males in relation to subsequent risk of any stroke.a
| Aerobic capacity (tertiles) | IRRs (95% CI) for medium aerobic capacity within strata of BMI | IRRs (95% CI) for low aerobic capacity within strata of BMI | ||||||
|---|---|---|---|---|---|---|---|---|
| High | Medium | Low | ||||||
| No. cases/total | IRR (95% CI) | No. cases/total | IRR (95% CI) | No. cases/total | IRR (95% CI) | |||
| BMI | ||||||||
| Normal | 1,747/457,912 | 1.00 | 4,436/479,732 | 1.20 (1.14, 1.28); P<0.001 | 9,265/489,701 | 1.66 (1.56, 1.76); P<0.001 | 1.20 (1.14, 1.28); P<0.001 | 1.66 (1.56, 1.76); P<0.001 |
| Overweight or obese | 338/57,590 | 1.65 (1.46, 1.85); P<0.001 | 656/40,754 | 2.07 (1.89, 2.27); P<0.001 | 537/21,605 | 2.36 (2.14, 2.60); P<0.001 | 1.26 (1.09, 1.43); P=0.002 | 1.43 (1.23, 1.63); P<0.001 |
| IRRs (95% CI) for BMI within strata of aerobic capacity | 1.65 (1.46, 1.85); P<0.001 | 1.72 (1.58, 1.86); P<0.001 | 1.42 (1.30, 1.55); P<0.001 | |||||
| Interaction on additive scale: RERI (95% CI) | 0.22 (−0.02, 0.47); P=0.07 | 0.05 (−0.22, 0.32); P=0.70 | ||||||
| Interaction on multiplicative scale: IRR ratio (95% CI) | 1.05 (0.90, 1.20); P=0.53 | 0.86 (0.74, 0.99); P=0.03 | ||||||
a
IRRs are adjusted for year of military conscription examination, muscular strength, family history of stroke, education, and neighborhood SES.
BMI = body mass index, IRR = incidence rate ratio, RERI = relative excess risk due to interaction.