Serum Albumin is Linearly and Negatively Associated With the Risk of All-cause and Cardiovascular Death in Coronary Heart Disease Patients.

Background: Despite advances in treatment and the potential role of serum albumin as a prognostic biomarker, the mortality rate of individuals with coronary heart disease (CHD) continues to increase. Thus, this study aimed to assess the relationship between serum albumin levels and the risk of all-cause mortality and cardiovascular death in individuals with CHD.

Methods: This large-scale retrospective cohort study included 1556 participants diagnosed with CHD from the National Health and Nutrition Examination Survey spanning 1999 to 2015. We conducted multivariate Cox regression, subgroup and sensitivity analyses, and restricted cubic spline (RCS) plots to examine the link between serum albumin levels and all-cause mortality and cardiovascular death.

Results: After gradually adjusting the confounding variables, serum albumin consistently demonstrated a strong link to increased overall and cardiovascular-related mortality risk when employed as a continuous variable (hazard ratio [HR]: 0.938, 95% confidence interval [CI]: 0.912-0.964; p < 0.001; HR: 0.921, 95% CI: 0.884-0.960; p < 0.001; respectively); meanwhile, serum albumin as a three-category variable, with Tertile 1 (T1, ≤40 g/L), Tertile 2 (T2, 40-43 g/L), and Tertile 3 (T3, >43 g/L), was only closely related to the risk of all-cause death (T2 vs. T1, HR: 0.771, 95% CI: 0.633-0.939; p = 0.010; T3 vs. T1, HR: 0.761, 95% CI: 0.612-0.947; p = 0.014; respectively). Subgroup analysis showed that serum albumin was linked to all-cause mortality across most groups (≤60 or >60 years, male or female, and without hypertension, diabetes, or chronic kidney disease); however, its correlation with cardiovascular death was observed only in the subgroup without hypertension (p < 0.05). The sensitivity analysis indicated that excluding participants with an estimated glomerular filtration rate <30 mL/min/1.73 m² did not alter the association between serum albumin and the risk of all-cause and cardiovascular mortality. Moreover, the RCS analysis further supported a consistent negative linear trend between serum albumin levels and mortality risks (p for nonlinearity >0.05).

Conclusions: The serum albumin levels in individuals with CHD were inversely and linearly related to all-cause mortality and cardiovascular death risk.