Association between the C-reactive protein–albumin–lymphocyte index and severity of acute coronary syndrome: A retrospective study

Background The C-reactive protein–albumin–lymphocyte index integrates inflammatory and nutritional markers. However, its role in acute coronary syndrome remains unclear. Methods We retrospectively analyzed 765 patients with acute coronary syndrome admitted to the Beijing Anzhen Hospital between January 2021 and December 2023. The C-reactive protein–albumin–lymphocyte index, neutrophil-to-lymphocyte ratio, C-reactive protein, and systemic immune–inflammation index were calculated from admission laboratories. Severe acute coronary syndrome was defined as ST-elevation myocardial infarction; mild acute coronary syndrome included non–ST-elevation myocardial infarction and unstable angina. Multivariable logistic regression was used to identify the predictors of severe acute coronary syndrome. Discriminative performance was assessed using receiver operating characteristic analysis with DeLong’s test. Results Lower C-reactive protein–albumin–lymphocyte index values were significantly associated with severe acute coronary syndrome (adjusted odds ratio: 0.91; 95% confidence interval: 0.86–0.95; p < 0.001) after adjustment for conventional risk factors. In receiver operating characteristic analysis, the C-reactive protein–albumin–lymphocyte index (area under the curve: 0.696; 95% confidence interval: 0.658–0.735) outperformed C-reactive protein (area under the curve: 0.599), neutrophil-to-lymphocyte ratio (area under the curve: 0.624), and systemic immune–inflammation index (area under the curve: 0.560) in discriminating severe from mild acute coronary syndrome (all p ≤ 0.001 for pairwise comparisons). Conclusions The C-reactive protein–albumin–lymphocyte index may help identify patients with more severe acute coronary syndrome and offers superior discrimination compared with established inflammatory and nutritional markers. Prospective studies are needed for validation.