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Table 4 Mortality rate ratios associated with NO 2 at the front door from 1971 onwards among 52 061 cohort participants, by potential effect modifiers

From: Traffic air pollution and mortality from cardiovascular disease and all causes: a Danish cohort study

Potential effect modifier Covariate level Mortality rate ratio (95% CI)a
   All causes Cardiovascular disease Ischemic heart disease Cerebrovascular disease
Whole cohortb   1.13 (1.04-1.23) 1.26 (1.06-1.51) 1.12 (0.85-1.47) 1.11 (0.78-1.63)
Sex Male 1.19 (1.07-1.32) 1.28 (1.05-1.56) 1.15 (0.85-1.54) 1.31 (0.84-2.04)
  Female 1.05 (0.94-1.19) 1.22 (0.93-1.60) 1.03 (0.65-1.53) 0.89 (0.53-1.50)
  p for interaction 0.08 0.74 0.66 0.20
School attendance (years) < 8 1.15 (1.03-1.29) 1.25 (1.00-1.56) 1.07 (0.76-1.50) 1.13 (0.68-1.87)
  8-10 1.16 (1.03-1.30) 1.34 (1.05-1.71) 1.17 (0.80-1.71) 1.02 (0.61-1.71)
  > 10 0.99 (0.83-1.19) 1.11 (0.76-1.61) 1.20 (0.65-2.23) 1.34 (0.64-2.78)
  p for interaction 0.22 0.79 0.65 0.80
Body mass index (kg/m2) < 25 1.12 (1.00-1.26) 1.13 (0.90-1.55) 1.14 (0.74-1.74) 0.99 (0.58-1.68)
  25-30 1.15 (1.02-1.29) 1.33 (1.06-1.67) 1.22 (0.85-1.73) 1.31 (0.81-2.13)
  > 30 1.13 (0.96-1.32) 1.24 (0.93-1.66) 0.96 (0.62-1.49) 0.92 (0.42-1.99)
  p for interaction 0.91 0.84 0.51 0.90
Physical activity (sport) No 1.17 (1.05-1.29) 1.25 (1.02-1.53) 1.15 (0.84-1.56) 1.05 (0.68-1.64)
  Yes 1.08 (0.95-1.22) 1.29 (1.01-1.66) 1.07 (0.72-1.59) 1.22 (0.72-2.07)
  p for interaction 0.25 0.80 0.75 0.63
Fruit and vegetable consumption (g/day) < 200 1.25 (1.11-1.42) 1.45 (1.13-1.87) 1.45 (0.98-2.14) 1.38 (0.79-2.37)
  200-400 1.06 (0.95-1.20) 1.23 (0.97-1.56) 1.10 (0.76-1.58) 1.29 (0.79-2.11)
  > 400 1.07 (0.93-1.23) 1.09 (0.82-1.47) 0.82 (0.51-1.31) 0.63 (0.32-1.24)
  p for interaction 0.04 0.12 0.05 0.08
Smoking status Never 1.18 (1.00-1.39) 1.29 (0.90-1.85) 1.35 (0.78-2.35) 0.79 (0.37-1.70)
  Former 1.05 (0.90-1.22) 1.02 (0.75-1.39) 0.97 (0.62-1.53) 0.99 (0.50-1.96)
  Current 1.15 (1.04-1.27) 1.36 (1.11-1.67) 1.13 (0.82-1.56) 1.27 (0.82-1.97)
  p for interaction 0.94 0.39 0.78 0.22
Pre-existing morbidityc at baseline No 1.13 (0.99-1.28) 1.43 (1.15-1.79) 1.38 (0.97-1.96) 1.18 (0.74-1.86)
  Yes 1.15 (1.04-1.26) 1.17 (0.94-1.60) 1.00 (0.72-1.40) 1.09 (0.66-1.79)
  p for interaction 0.79 0.13 0.13 0.79
  1. aPer doubling of NO2 concentration. Adjusted for sex, age (age was the time scale), calendar year, employment status, school attendance, occupation with potential exposure to smoke and fumes, smoking status, smoking intensity, smoking duration, environmental tobacco smoke, alcohol intake, fat, fish, fruit and vegetables, fiber, folate, body mass index, waist circumference, physical activity with sport, hormone replacement therapy, average gross income of municipality of residence in 1995 and noise at the baseline address. The Cox model stratified for marital status.
  2. bIdentical to estimates in the last column of Table2; shown here for comparison.
  3. cMyocardial infarction, angina pectoris, stroke, hypertension, hypercholesterolemia or diabetes mellitus. The model included adjustment for main effects of pre-existing morbidity.