Life’s Essential 8 moderates the association between Occupational Hazard Index and the incidence of hypertension among steelworkers: a prospective cohort study

Background Occupational hazards are prevalent among steelworkers and have been linked to an elevated risk of hypertension. However, whether favourable cardiovascular health mitigates this association remains unclear. This study aimed to investigate the moderating role of Life’s Essential 8 (LE8) in the relationship between the Occupational Hazard Index (OHI) and incident hypertension in this population. Methods We analysed 5,908 hypertension-free steelworkers from the Beijing–Tianjin–Hebei occupational cohort. OHI was derived from 22 workplace hazard factors using a Euclidean norm model, and LE8 was scored from eight cardiovascular health metrics. Cox proportional hazards models, restricted cubic splines, multiplicative and additive interaction tests, joint-effect and subgroup analyses, and sensitivity analyses were performed. Incremental predictive value was assessed using the C-index, net reclassification index (NRI) and integrated discrimination improvement (IDI). Results Over 8 years of follow-up, 2,199 participants (37.22%) were diagnosed with incident hypertension. High OHI was associated with increased risk (HR = 1.59, 95% CI 1.46–1.73), with a 35.4% increase per 1-SD increment (HR = 1.354, 95% CI 1.292–1.418), whereas high LE8 was associated with reduced risk (HR = 0.407, 95% CI 0.340–0.489; 23.3% reduction per 1-SD increment, HR = 0.767, 95% CI 0.736–0.800). Stratified restricted cubic spline analyses showed that the non-linear positive OHI–hypertension association was steepest at low LE8 and flattened progressively at higher LE8 levels. Significant multiplicative (P for interaction < 0.001) and additive interactions were observed. Relative to the low LE8 + high OHI group, the high LE8 + high OHI group had a 44% lower risk (HR = 0.560, 95% CI: 0.455–0.689) and the high LE8 + low OHI group a 69.1% lower risk (HR = 0.309, 95% CI: 0.239–0.399). Excluding cases diagnosed within the first year of follow-up did not materially alter the results. Adding OHI and LE8 to conventional risk factors improved model performance (C-index, 0.658 to 0.686; NRI = 0.151; IDI = 0.022). Conclusions LE8 significantly moderates the OHI–hypertension association in steelworkers, and a higher LE8 may partly offset the hypertensive effects of occupational hazards. Reducing occupational exposure while improving cardiovascular health may maximise hypertension prevention.