Higher oxidative balance was associated with lower all-cause mortality, and greater systemic inflammation was associated with higher mortality among patients with rheumatoid arthritis, according to a retrospective cohort study published in Medicine.
The analysis included 24,552 adults from the National Health and Nutrition Examination Survey (2007 to 2018), including 812 patients with rheumatoid arthritis, with mortality follow-up through 2019.
After adjustment for demographic and clinical factors, each 1-point increase in oxidative balance score was associated with a 4% lower mortality risk. Patients with higher oxidative balance scores had a 37% lower mortality risk compared with those with lower scores. In contrast, each 1-unit increase in systemic inflammation response index was associated with a 14% higher mortality risk, and patients with higher levels had more than twice the mortality risk of those with lower levels.
When considered jointly, patients with high systemic inflammation and low oxidative balance had the poorest survival, whereas those with low inflammation and high oxidative balance had the most favorable outcomes, as shown in Kaplan-Meier analyses.
Oxidative balance was assessed using a composite score derived from dietary intake and lifestyle factors, while systemic inflammation was measured using the systemic inflammation response index, calculated from neutrophil, monocyte, and lymphocyte counts.
The investigators also identified a modest inverse association between oxidative balance and inflammation. Mediation analysis suggested that improved oxidative balance may reduce mortality risk in part by attenuating systemic inflammation, which accounted for approximately 15% of the observed association.
In subgroup analyses, a higher oxidative balance score was associated with lower mortality primarily among patients with elevated inflammation; however, this finding fell short of the conventional threshold for statistical significance in fully adjusted models. No significant association was observed among patients with lower inflammatory levels.
The authors also identified potential risk thresholds, noting that systemic inflammation response index values above 1.073 were associated with increased mortality risk, while oxidative balance scores at or below 18.482 may identify patients at elevated risk, suggesting a possible role for risk stratification at diagnosis.
The findings should be interpreted in the context of several limitations. Oxidative balance and inflammatory status were measured at a single time point, limiting assessment of longitudinal changes. The oxidative balance score incorporated 24-hour dietary recall data and lifestyle factors, which may introduce measurement error, and the diagnosis of rheumatoid arthritis was based on self-report. Residual confounding cannot be excluded, and the observational design does not establish causality.
The researchers reported no conflicts of interest. The study was supported by grant funding.
Source: Medicine