Relationship between the Red Blood Cell Distribution Width-to-Albumin Ratio and the Risk of Chest Pain and Mortality among U.S. Adults: Evidence from the NHANES 2007–2016

Background The red blood cell distribution width-to-albumin ratio (RAR) is an emerging inflammatory marker associated with increased mortality from various diseases. However, the potential link between the RAR and the occurrence of chest pain is not thoroughly elucidated. Therefore, we assessed the relationships of the RAR with chest pain and all-cause mortality (regardless of chest-pain status). Methods We analyzed National Health and Nutrition Examination Survey (NHANES, 2007–2016) data with a combined cross-sectional/cohort design. We assessed the RAR–chest pain association via univariate/multivariate logistic regression analyses, which yielded odds ratios (ORs) and 95% confidence intervals (CIs). The dose‒response RAR–chest pain relationship was examined using restricted cubic spline (RCS) analysis, validated through subgroup analyses, and visualized through forest plots. The RAR–all-cause mortality relationship was evaluated via Kaplan–Meier survival curves and log-rank tests. Additionally, hazard ratios (HRs) and 95% CIs for mortality risk were estimated via weighted Cox proportional hazards models. Potential linear or nonlinear trends for the RAR–mortality association were explored via RCS functions. Results The results revealed a significant positive RAR–chest pain association, even after confounder adjustment (quartile 4 vs. quartile 1: OR=1.27, 95% CI=1.01–1.60; P=0.038). Over a median 91.2-month follow-up, 1,731 individuals (14.1%) died. In the fully adjusted Model 3 (multivariate Cox regression), the estimated HR for overall mortality was 2.28 (95% CI=1.99–2.60) among all participants, 2.87 (95% CI=2.17–3.80) among individuals reporting chest pain, and 2.02 (95% CI=1.70–2.41) among those without chest pain ( P < 0.001; Table 3). When the continuous RAR was categorized into quartiles, participants in the highest quartile presented a 107% greater risk of death than those in the lowest quartile (95% CI=1.68–2.55) after full covariate adjustment. RCS modeling further confirmed a linear/positive dose‒response relationship between the RAR and all-cause mortality in all participants (nonlinear P=0.6971) and both the chest pain (nonlinear P=0.1180) and without chest pain (nonlinear P=0.5342) subgroups. Conclusion Our research revealed that the RAR is positively correlated with the occurrence of chest pain. Furthermore, regardless of chest pain status, an elevated RAR was associated with increased all-cause mortality risk, suggesting that the RAR can serve as a valuable chest pain and overall mortality predictor in the general population.