Table 2.

Characteristics of cases and controls

Cases* (n = 594)Controls* (n = 1,041)P
Gender
    Male (%)82.340.1<0.01
Mean age, y (SD)44.4 (9.8)36.6 (9.8)<0.01
Mean BMI (SD)18.9 (2.6)20.0 (3.4)<0.01
Mean education level, y (SD)2.7 (3.5)3.5 (3.9)<0.01
Cigarette smoking status
    Ever-smokers in men, %82.676.30.02
    Ever-smokers in women, %15.26.7<0.01
Drinking duration of baseline well, y8.9 (5.9)7.1 (5.1)
Baseline well arsenic, μg/L159.2 (157.1)92.6 (106.4)<0.01
Drinking duration with known arsenic levels, y11.9 (8.2)9.1 (6.9)
Time-weighted well arsenic, μg/L158.3 (155.5)90.5 (101.9)
Mean total urinary arsenic, μg/L (SD)205.5 (242.2)133.0 (147.6)<0.01
Mean urinary creatinine, g/L (SD)59.5 (45.8)59.9 (46.3)0.88
Mean urinary %InAs (SD)15.4 (6.2)15.8 (7.2)0.28
Mean urinary %MMA (SD)14.8 (5.0)12.6 (4.9)<0.01
Mean urinary %DMA (SD)69.0 (8.6)70.7 (8.6)<0.01
Mean PMI MMA/(AsIII + AsV) (SD)1.10 (0.53)0.95 (0.81)<0.01
Mean SMI (DMA/MMA) (SD)5.42 (2.74)6.77 (3.66)<0.01
  • * Data were missing on BMI for cases and controls, respectively, 5 and 7 subjects; on drinking duration and TWA for 38 and 15 subjects; on PMI for 1 and 3 subjects (due to that %InAs = 0); on SMI for 1 and 6 subjects (due to that %MMA = 0); and on betel nut use for 3 and 1 subjects.