Table 3

Mean differences (95% CIs) in pulse rate and blood pressure, and odds ratios (95% CIs) of hypertension subtypes, by tertiles of accumulated noise exposure time*

Current exposed (0–18.8 years)Tertiles of accumulated exposure timep For trend
Short (0–0.3 years)Medium (0.4–1.5 years)Long (1.6–18.8 years)
Pulse rate (bpm)
 Model 1−2.34 (−3.46 to −1.23)−1.19 (−2.79 to 0.41)−2.90 (−4.50 to −1.30)−2.94 (−4.49 to −1.39)<0.001
 Model 2−1.29 (−2.50 to −0.08)−0.59 (−2.38 to 1.21)−1.81 (−3.49 to −0.13)−1.49 (−3.06 to 0.08)0.019
 Model 3−1.27 (−2.62 to 0.09)−0.83 (−2.78 to 1.13)−1.59 (−3.36 to 0.18)−1.38 (−3.47 to 0.72)0.038
Systolic blood pressure (mm Hg)
 Model 11.84 (0.74 to 2.94)0.53 (−1.23 to 2.29)1.51 (−0.58 to 3.60)3.52 (1.79 to 5.24)<0.001
 Model 20.38 (−0.67 to 1.42)1.39 (−0.10 to 2.87)0.25 (−1.63 to 2.13)−0.55 (−2.32 to 1.22)0.879
 Model 30.39 (−0.90 to 1.67)1.56 (−0.16 to 3.28)0.11 (−2.03 to 2.24)−0.54 (−2.44 to 1.37)0.850
Diastolic blood pressure (mm Hg)
 Model 11.62 (0.72 to 2.53)−0.13 (−1.37 to 1.11)1.69 (0.02 to 3.36)3.33 (1.97 to 4.69)<0.001
 Model 20.58 (−0.29 to 1.46)−0.08 (−1.24 to 1.07)0.71 (−0.78 to 2.21)1.14 (−0.20 to 2.49)0.077
 Model 30.74 (−0.40 to 1.88)0.03 (−1.54 to 1.59)1.22 (−0.50 to 2.95)0.97 (−0.49 to 2.44)0.102
Isolated systolic hypertension§
 Model 10.89 (0.68 to 1.17)0.49 (0.24 to 0.99)0.96 (0.52 to 1.75)1.26 (0.91 to 1.73)0.673
 Model 20.98 (0.73 to 1.33)0.61 (0.30 to 1.21)1.07 (0.57 to 1.99)1.24 (0.86 to 1.81)0.179
 Model 31.36 (0.93 to 1.99)1.20 (0.54 to 2.67)1.53 (0.74 to 3.18)1.32 (0.81 to 2.17)0.133
Isolated diastolic hypertension§
 Model 12.03 (1.33 to 3.09)1.58 (0.94 to 2.66)1.64 (0.88 to 3.04)2.92 (1.71 to 4.98)<0.001
 Model 21.43 (0.90 to 2.25)1.22 (0.70 to 2.13)1.15 (0.58 to 2.26)1.90 (1.07 to 3.37)0.058
 Model 31.52 (0.92 to 2.53)1.12 (0.60 to 2.10)1.26 (0.58 to 2.74)2.23 (1.21 to 4.12)0.025
Systodiastolic hypertension§
 Model 11.02 (0.70 to 1.50)1.31 (0.76 to 2.27)1.12 (0.60 to 2.07)0.64 (0.31 to 1.34)0.584
 Model 20.96 (0.77 to 1.19)1.73 (0.97 to 3.05)1.26 (0.64 to 2.49)0.54 (0.25 to 1.17)0.473
 Model 31.00 (0.61 to 1.64)1.80 (0.94 to 3.42)1.06 (0.48 to 2.38)0.45 (0.19 to 1.08)0.237
Self-reported hypertension§
 Model 10.97 (0.78 to 1.21)0.84 (0.60 to 1.17)0.88 (0.59 to 1.31)1.22 (0.93 to 1.61)0.651
 Model 21.10 (0.87 to 1.39)1.22 (0.89 to 1.69)1.03 (0.66 to 1.62)1.07 (0.78 to 1.46)0.611
 Model 31.12 (0.86 to 1.47)1.21 (0.85 to 1.72)1.10 (0.69 to 1.75)1.08 (0.76 to 1.54)0.562
General hypertension§
 Model 11.07 (0.88 to 1.30)0.86 (0.65 to 1.15)1.08 (0.73 to 1.61)1.30 (1.01 to 1.66)0.144
 Model 21.17 (0.93 to 1.46)1.25 (0.93 to 1.68)1.24 (0.79 to 1.95)1.04 (0.77 to 1.40)0.409
 Model 31.18 (0.93 to 1.50)1.16 (0.83 to 1.63)1.29 (0.80 to 2.07)1.09 (0.79 to 1.51)0.307
  • * The never exposed group was the reference category, please see table 1 for sample size in each column. Model 1 was bivariable analysis; model 2 adjusted for age, sex, ethnicity, BMI, educational level, physical activity, cigarette smoking and diabetes; model 3 additionally adjusted for annual family income, pack-years of cigarette smoking, passive smoking in the workplace or at home, alcohol drinking, waist circumference and total cholesterol.

  • p Is for linear trend across tertile groups.

  • β Coefficient (95% CI) from linear regression represents mean difference between a specific exposed group and the never exposed group.

  • § Odds ratio (95% CI).

  • Systolic blood pressure ≥140 mm Hg, diastolic blood pressure ≥90 mm Hg, or self-reported hypertension.