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Table 1 Baseline characteristics of the cohort (n = 628)

From: Modification by hemochromatosis gene polymorphisms of the association between traffic-related air pollution and cognition in older men: a cohort study

   HFE C282Y HFE H63D
  All (n = 628) Wild type (n = 540) Variant (n = 88) Wild type (n = 469) Variant (n = 159)
Variable, mean ± SD
   Age, years 70.0 ± 7.1 70.1 ± 7.1 69.5 ± 7.1 70.0 ± 7.3 70.2 ± 6.3
   Education, years 14.4 ± 2.6 14.4 ± 2.7 14.4 ± 2.4 14.5 ± 2.7 14.3 ± 2.5
   Black carbon concentration, μg/m3 0.58 ± 0.28 0.58 ± 0.28 0.57 ± 0.27 0.59 ± 0.29 0.56 ± 0.24
   Body mass index, kg/m2 27.9 ± 3.9 27.9 ± 4.0 28.0 ± 3.7 28.0 ± 4.1 27.6 ± 3.5
   Physical activity, MET-hr/week 16.6 ± 20.1 16.3 ± 19.9 18.0 ± 21.8 16.7 ± 20.6 16.3 ± 18.8
   % of census tract: adults with a college degree 39.9 ± 16.5 40.3 ± 16.8 37.1 ± 14.5 40.2 ± 16.5 39.1 ± 16.8
   % of census tract: non-white 10.9 ± 11.4 10.9 ± 11.1 10.4 ± 13.0 10.4 ± 10.6 12.3 ± 13.4
Variable, n (%)
   Diabetic 94 (15.0) 79 (14.6) 15 (17.0) 69 (14.7) 25 (15.7)
   Hypertensive 415 (66.1) 367 (68.0) 48 (54.5) 304 (64.8) 111 (69.8)
   Smoking      
    Never 185 (29.5) 161 (29.8) 24 (27.3) 140 (29.9) 45 (28.3)
    Former 410 (65.3) 351 (65.0) 59 (67.0) 302 (64.4) 108 (67.9)
    Current 33 (5.3) 28 (5.2) 5 (5.7) 27 (5.8) 6 (3.8)
   Consume ≥2 alcoholic drinks per day 157 (25.0) 137 (25.4) 20 (22.7) 122 (26.0) 35 (22.0)
   Consume dark fish ≥1/week 94 (15.0) 81 (15.0) 13 (14.8) 68 (14.5) 26 (16.4)
   English as first language 538 (85.7) 454 (84.1) 84 (95.5) 400 (85.3) 138 (86.8)
   Has computer experience 255 (40.6) 218 (40.4) 37 (42.0) 193 (41.2) 62 (39.0)
  1. Abbreviations: HFE, hemochromatosis gene; SD, standard deviation; MET-hr/week, metabolic equivalent hours per week.