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Table 1 Characteristics of the study population overall and by NHANES cycle

From: Construction of environmental risk score beyond standard linear models using machine learning methods: application to metal mixtures, oxidative stress and cardiovascular disease in NHANES

  Cycle Overall
2003-2004 2005-2006 2007-2008 2009-2010 2011–2012 2013-2014
N = 1443 N = 1418 N = 1664 N = 1884 N = 1557 N = 1698 N = 9664
CONTINUOUS, mean(SD)
 Age, years 51.0 (19.5) 48.3 (18.8) 50.2 (17.6) 49.4 (17.8) 48.0 (17.7) 48.3 (17.2) 49.2 (17.2)
 BMI, kg/m2 28.6 (6.32) 28.7 (6.70) 28.7 (6.13) 29.1 (6.86) 28.7 (6.90) 29.1 (7.11) 28.8 (6.69)
 GGT, U/L 21.5 (1.91) 20.85 (1.96) 24.1 (1.92) 22.1 (1.92) 20.5 (1.92) 21.3 (1.96) 21.7 (1.94)
 SBP, mm Hg 126.0 (20.7) 123.0 (19.3) 123.7 (18.6) 121.9 (18.4) 122.5 (17.8) 122.6 (17.5) 123.2 (18.7)
 DBP, mm Hg 70.3 (12.3) 69.1 (12.7) 70.4 (11.8) 69.0 (12.2) 71.0 (11.8) 70.2 (11.3) 70.0 (12.0)
CATEGORICAL, N (%)
 Female 839 (52.08) 825 (51.79) 966 (50.31) 1078 (52.00) 871 (49.77) 961 (51.72) 4911 (50.82)
 Race/Ethnicity
  Mexican American 323 (20.05) 311 (19.52) 322 (16.77) 384 (18.52) 154 (8.80) 267 (14.37) 1618 (16.74)
  Other Hispanic 39 (2.42) 47 (2.95) 234 (12.19) 217 (10.47) 179 (10.23) 159 (8.56) 779 (8.06)
  Non-Hispanic White 852 (52.89) 816 (51.22) 893 (46.51) 973 (46.94) 639 (36.51) 805 (43.33) 4501 (46.57)
  Non-Hispanic Black 341 (21.17) 363 (22.79) 402 (20.94) 372 (17.95) 458 (26.17) 370 (19.91) 1976 (20.45)
  Other 56 (3.48) 56 (3.52) 69 (3.59) 127 (6.13) 320 (18.29) 257 (13.83) 790 (8.17)
 Smoking Status
  Never 830 (51.55) 843 (52.92) 1015 (52.89) 1116 (53.84) 1002 (57.29) 1044 (56.19) 5242 (54.24)
  Former 337 (20.93) 338 (21.22) 428 (22.30) 444 (21.42) 340 (19.44) 376 (20.24) 2000 (20.70)
  Current 443 (27.52) 412 (25.86) 476 (24.80) 513 (24.75) 407 (23.27) 438 (23.57) 2422 (25.06)
 Education
   < High School 486 (30.25) 450 (28.28) 611 (31.82) 591 (28.55) 420 (24.03) 393 (21.16) 2599 (26.89)
  High School 850 (52.89) 836 (52.54) 966 (50.32) 1082 (52.27) 872 (49.89) 996 (53.64) 5018 (51.92)
  College or Above 271 (16.86) 305 (19.17) 343 (17.86) 397 (19.18) 456 (26.09) 468 (25.20) 2047 (21.18)
 Hypertension 549 (40.76) 450 (33.06) 608 (37.98) 666 (36.78) 550 (36.74) 595 (36.28) 3418 (36.92)
 Mortality        
  Total 163 (11.32) 102 (7.19) 62 (3.73) 32 (1.70) NA NA 359 (5.61)
  CVD 42 (2.92) 33 (2.33) 17 (1.02) 2 (0.11) NA NA 94 (1.47)
  Cancer 38 (2.64) 25 (1.76) 14 (0.84) 13 (0.69) NA NA 90 (1.41)
  1. BMI body mass index, GGT gamma-glutamyl transferase, SBP systolic blood pressure, DBP diastolic blood pressure, CVD cardiovascular disease