Associations of oxidative balance score with mortality and cardiovascular events: cohort study from NHANES and UK Biobank

Objective To investigate the associations of oxidative balance score (OBS) with all-cause mortality, cardiovascular mortality and cardiovascular disease (CVD) incidence in two large, population-based cohorts. Design Cohort study and cross-sectional study were used. Setting The US National Health and Nutrition Examination Survey (NHANES) and the UK Biobank. Participants A total of 33 566 adults from NHANES (1998–2018) and 55 760 adults from the UK Biobank were included. Main outcome measures All-cause mortality, cardiovascular mortality and CVD. Mortality outcomes were ascertained through national death registries. Prevalent CVD was identified in NHANES through questionnaire, and incident CVD events were identified in the UK Biobank using linked hospital admission and death registry data. Results Higher OBS was consistently associated with lower all-cause and cardiovascular mortality in both cohorts. In NHANES, participants in the highest OBS quartile (Q4) had a 39% lower risk of all-cause mortality (adjusted HR: 0.61, 95% CI 0.52 to 0.72) and a 45% lower risk of cardiovascular mortality (adjusted HR: 0.55, 95% CI 0.41 to 0.74) compared with those in Q1. Similarly, in the UK Biobank, Q4 was associated with an 18% lower risk of all-cause mortality (adjusted HR: 0.82, 95% CI 0.74 to 0.91) and a 41% lower risk of cardiovascular mortality (adjusted HR: 0.59, 95% CI 0.4 to 0.87). In NHANES, Q4 was associated with lower odds of prevalent CVD (adjusted OR: 0.56, 95% CI 0.46 to 0.67), whereas in the UK Biobank, Q4 was associated with a 19% lower risk of incident CVD during follow-up (adjusted HR: 0.81, 95% CI 0.74 to 0.9). Subgroup analyses in NHANES indicated heterogeneity by ethnicity and socioeconomic status, whereas associations in the UK Biobank followed an L-shaped pattern with a flattening of estimated risk at moderate OBS levels. Conclusion Higher OBS was associated with more favourable mortality and cardiovascular outcomes. These findings indicate that OBS is a composite indicator associated with cardiovascular health at the population level.