C-reactive protein-to-serum albumin ratio as a novel predictor of long-term outcomes in coronary artery disease patients who have undergone percutaneous coronary intervention: analysis of a real-world retrospective cohort study

C-reactive protein (CRP) has been proposed as a contributor to the pathogenesis of coronary artery disease (CAD) and inflammatory reactions, which are associated with a decrease in serum albumin, and it has been reported that the CRP-to-serum albumin ratio (CAR) can predict CAD severity in inpatient ischemic cardiomyopathy (ICM) patients. However, the relationship between the CAR and long-term adverse outcomes in CAD patients after percutaneous coronary intervention (PCI) is still unknown.A total of 3561 CAD patients enrolled in the Outcomes and Risk Factors of Patients with Coronary Heart Disease after PCI: an investigation based on case records and follow-up (CORFCHD-ZZ), a retrospective cohort study conducted from January 2013 to December 2017, and 1630 patients meeting the study inclusion criteria were divided into two groups based on the CAR (CAR < 0.186; n = 1301 and CAR ≥ 0.186; n = 329). The primary outcome was long-term mortality, including all-cause mortality (ACM) and cardiac mortality. The average follow-up time was 37.59 months.We found that there were significant differences between the two groups in the incidences of ACM (P < 0.001) and cardiac mortality (P = 0.003). Cox multivariate regression analyses demonstrated that CAR was an independent predictor of ACM [hazard ratio, 2.678; (95% confidence interval (CI), 1.568-4.576); P < 0.001] and cardiac mortality (hazard ratio, 2.055; 95% CI, 1.056-3.998; P = 0.034) in CAD patients after PCI.This study revealed that the CAR is an independent and novel predictor of long-term adverse outcomes in CAD patients who have undergone PCI.