Non-linear Association of CAR with all-Cause and Cardiovascular Mortality in Coronary Heart Disease: A Retrospective Cohort Study from NHANES.

Objective: To investigate the relationship between C-reactive protein and albumin ratios (CAR) and all-cause and cardiovascular disease(CVD)-specific mortality in individuals with coronary heart disease(CHD).

Methods: The data from 1895 patients were extracted from the National Health and Nutrition Examination Survey (NHANES) database from 1999-2010. We used weighted COX regression analyses to explore the association between CAR, all-cause, and CVD-specific mortality. Restricted cubic spline(RCS) regression models and threshold effects analysis were used to analyze nonlinear relationships. Subgroup analyses were also performed to explore these relationships further.

Results: During a mean follow-up of 115.78 months, 61.48% of deaths occurred, and 21.85% were due to CVD. After adjusting for potential confounders, each 1-unit increase in CAR was associated with a 65% increase in all-cause mortality and a 67% increase in CVD-specific mortality. The RCS model revealed a non-linear association between CAR and the risk of all-cause mortality and CVD-specific mortality in CHD patients (all non-linear P < 0.001). Threshold effects analysis identified inflection points in regression models of all-cause mortality (0.04, P < 0.001) and CVD-specific mortality (0.05, P = 0.0024). The interaction tests found sex, smoking and diabetes influenced the association between CAR and all-cause mortality and sex, smoking and HF influenced its association with CVD-specific mortality (all P < 0.05).

Conclusion: There was a nonlinear association between CAR and all-cause mortality and CVD mortality in patients with CHD, with a higher hazard ratio before the inflection point. Sex, smoking, diabetes, and HF might have an effect on the associations between CAR and death risks.