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Table 3 Attributing effects to additive interaction between term birth weight and lifestyle on risks of hypertension*

From: Joint association between birth weight at term and later life adherence to a healthy lifestyle with risk of hypertension: a prospective cohort study

  ALL Baseline age (years)
≤30 31–35 ≥36
(n = 8,652) ** (n = 17,237) ** (n = 26,315) **
Main Effects     
 Lower birth weight at term (per kg) 1.23 (1.11–1.36) 1.22 (0.88–1.69) 1.25 (1.03–1.51) 1.21 (1.06–1.37)
 Unhealthy lifestyle (per score) *** 1.61 (1.51–1.71) 1.73 (1.41–2.12) 1.67 (1.48–1.88) 1.55 (1.43–1.68)
 Joint effect 1.95 (1.83–2.07) 2.13 (1.74–2.52) 2.05 (1.82–2.28) 1.86 (1.70–2.01)
Relative excess risk due to interaction (RERI)    
 RERI 0.12 (0.09–0.15) 0.18 (0.05–0.31) 0.14 (0.07–0.20) 0.10 (0.07–0.13)
P <0.0001 0.006 <0.0001 <0.0001
Attributable proportion, %     
 Lower birth weight at term (per kg) 23.9 (16.6–31.2) 19.3 (–2.3–40.9) 23.7 (11.1–36.2) 24.2 (14.0–34.4)
 Unhealthy lifestyle 63.7 (60.4–66.9) 64.8 (55.6–74.0) 63.5 (57.8–69.2) 64.0 (59.6–68.4)
 Additive interaction 12.5 (9.9–15.0) 15.9 (8.9–22.9) 12.9 (8.6–17.1) 11.8 (8.0–15.6)
  1. * Multivariable adjusted relative risk estimated from Cox proportional hazards models adjusted for age, ethnicity (Caucasian, yes/no), family history of hypertension (yes/no), use of oral contraceptive pills (never, past or current), smoking status (never smoker, former smoker, current smoker: 1–14, 15–24 or ≥25 cigarettes/d), and supplemental folic acid intake (no, <400, 400–800, or >800 μg/d)
  2. ** Baseline sample size
  3. *** Unhealthy lifestyles include exercise <3.5 hours/week at moderate intensity, diet in bottom 4 quintiles of the DASH score, BMI ≥25 kg/m2, and not moderate alcohol consumption (moderate: 1 to 10 g alcohol/d) and use of nonnarcotic analgesic medications at least once per week