Cardiovascular composite events and the healthy worker effect among noise-exposed workers: a retrospective cohort study.

BACKGROUND

Occupational noise exposure is prevalent, but its cardiovascular effects are under recognized. Most studies are cross-sectional, focus on single endpoints, and rarely account for the healthy worker effect (HWE). This study aimed to identify risk factors for cardiovascular composite events in noise-exposed workers and further assess this effect.

METHODS

This retrospective cohort study enrolled 1,381 noise-exposed workers with normal blood pressure and normal electrocardiogram at baseline in 2020. All participants were followed annually through 2023. The primary endpoint was a composite cardiovascular event (hypertension or electrocardiographic abnormality). Cox proportional hazards models were used to identify associated factors. Restriction analysis, restricted cubic spline analysis, and sensitivity analyses were performed to assess robustness.

RESULTS

Multivariable Cox regression identified systolic blood pressure (SBP) (HR = 1.012, 95% CI 1.005-1.020, p < 0.001) and smoking (HR = 1.191, 95% CI 1.029-1.377, p = 0.019) as independent risk factors. Work duration >120 months showed an apparent protective effect (HR = 0.621, 95% CI 0.466-0.826, p = 0.001). After excluding pre-employment workers, the reduced risk for >120 months persisted (HR = 0.787, 95% CI 0.638-0.969, p = 0.024). Forcing age into the multivariable model did not materially change the effect estimates. Sensitivity analysis showed that baseline SBP ≥ 130 mmHg was associated with a 66.3% increased risk of composite events (HR = 1.663, 95% CI 1.327-2.085, p < 0.001). For the hypertension endpoint, combined exposure to noise and dust (HR = 1.896, 95% CI 1.219-2.949, p = 0.005) and combined exposure to noise and chemical agents (HR = 1.580, 95% CI 1.013-2.463, p = 0.044) significantly increased risk.

CONCLUSION

Smoking and elevated SBP are independent risk factors for cardiovascular composite events in noise-exposed workers. The apparent protective effect of work duration is consistent with the HWE. Combined exposure to noise with dust or chemical agents significantly increases the risk of hypertension.