Table 7– Logistic regression dose–response model in nonsmokers, with the primary exposure variable of well water arsenic and the outcome variable of interest of the presence or absence of dyspnoea
Independent variablesCrude OR (95% CI)p-valueAdjusted OR (95% CI)p-value
Well arsenic quintile#
 1: reference1.001.00
 21.39 (0.99–1.93)0.0521.36 (0.97–1.90)0.074
 31.97 (1.44–2.70)<0.0011.96 (1.43–2.70)<0.001
 42.17 (1.59–2.95)<0.0012.14 (1.56–2.92)<0.001
 51.84 (1.34–2.53)<0.001**1.80 (1.31–2.49)<0.001**
Age1.03 (1.02–1.04)<0.001
Education0.96 (0.94–0.99)0.004
Sex1.65 (1.24–2.19)0.001
Systolic BP1.00 (0.99–1.01)0.323
BMI group
 11.21 (0.99–1.47)0.064
 21.29 (0.93–1.79)0.122
  • BP: blood pressure; BMI: body mass index. #: the reference well water arsenic concentration was <7 μg·L−1, with quintiles as described in table 1; : BMI categorised as low (<18.5 kg·m−2; group 1) and high (≥25 kg·m−2; group 2). **: p<0.01 by Chi-squared test for trend.