Table 4

 Joint effects of shift work (SW), noise, and physical workload (PW) on risk of coronary heart disease (CHD) risk among industrially employed men for different follow ups

n/CHD casesUnadjustedAge adjustedSBP–TotC–Smo–BMI adjustedBlue-/white-collar adjusted
RR95% CIRR95% CIRR95% CIRR95% CI
The relative risks (RR) with 95% confidence intervals (95% CI) and p value were derived using Cox proportional hazards models with different covariates.
SBP, systolic blood pressure; TotC, total serum cholesterol; Smo, smoking; BMI, body mass index.
*p<0.05; **p<0.01; ***p<0.001.
†PW+ when product of prevalence (P) and level (L) is in 3 tertile.
Shift work + noise
Fu –95SW−, no746/721111
SW−, continuous310/341.13(0.75–1.71)1.10(0.73–1.65)1.08(0.72–1.63)1.05(0.65–1.70)
SW−, both84/141.78(1.01–3.16)*1.72(0.97–3.05)1.60(0.90–2.83)1.65(0.88–3.09)
SW+, no194/271.47(0.94–2.28)1.45(0.93–2.26)1.31(0.84–2.04)1.40(0.87–2.24)
SW+, continuous370/561.62(1.14–2.30)**1.65(1.16–2.34)**1.46(1.03–2.08)*1.50(0.97–2.32)
SW+, both100/131.36(0.76–2.46)1.40(0.78–2.53)1.21(0.67–2.18)1.26(0.66–2.40)
Fu –99SW−, no746/1211111
SW−, continuous310/521.04(0.75–1.43)0.99(0.72–1.37)1.00(0.72–1.39)0.88(0.60–1.28)
SW−, both84/231.82(1.16–2.84)**1.74(1.11–2.72)*1.67(1.07–2.60)*1.54(0.95–2.50)
SW+, no194/411.34(0.94–1.92)1.33(0.93–1.89)1.23(0.87–1.76)1.21(0.83–1.76)
SW+, continuous370/821.43(1.08–1.89)*1.45(1.10–1.93)**1.31(0.99–1.74)1.21(0.86–1.70)
SW+, both100/251.59(1.03–2.44)*1.65(1.07–2.54)*1.43(0.93–2.21)1.35(0.84–2.16)
Shift work + physical workload
Fu –95SW−, PW−748/351111
SW−, PW+392/231.20(0.83–1.73)1.17(0.81–1.70)1.11(0.77–1.60)1.08(0.69–1.68)
SW+, PW−448/351.43(1.02–2.01)*1.45(1.04–2.03)*1.26(0.90–1.77)1.31(0.88–1.95)
SW+, PW+216/181.65(1.10–2.47)*1.67(1.12–2.51)*1.50(1.00–2.26)*1.49(0.92–2.39)
Fu –99SW−, PW−748/1171111
SW−, PW+392/791.32(0.99–1.76)1.29(0.97–1.71)1.25(0.94–1.67)1.18(0.83–1.67)
SW+, PW−448/941.39(1.06–1.82)*1.41(1.08–1.85)*1.26(0.96–1.65)1.26(0.92–1.73)
SW+, PW+216/541.69(1.22–2.33)**1.72(1.25–2.38)***1.58(1.14–2.18)**1.51(1.03–2.20)*
Noise + physical workload†
Fu –95No, PW−820/391111
Continuous, PW−376/311.43(1.01–2.02)*1.43(1.01–2.02)*1.30(0.92–1.83)1.29(0.84–2.00)
No, PW+120/91.36(0.80–2.32)1.34(0.78–2.28)1.24(0.72–2.11)1.23(0.68–2.23)
Continuous, PW+304/201.21(0.82–1.79)1.20(0.81–1.76)1.18(0.80–1.74)1.10(0.69–1.76)
Both, PW+184/121.48(0.96–2.29)1.48(0.96–2.28)1.33(0.86–2.06)1.34(0.81–2.23)
Fu –99No, PW−820/1341111
Continuous, PW−376/771.29(0.98–1.71)1.29(0.98–1.71)1.19(0.90–1.58)1.11(0.79–1.57)
No, PW+120/281.50(1.00–2.25)1.47(0.98–2.21)1.40(0.93–2.11)1.29(0.82–2.03)
Continuous, PW+304/571.17(0.85–1.59)1.14(0.83–1.55)1.15(0.84–1.57)1.00(0.69–1.45)
Both, PW+184/481.68(1.21–2.33)**1.68(1.21–2.34)**1.54(1.10–2.14)*1.44(0.98–2.12)