Age modulates the relationship between platelet-to-lymphocyte ratio and coronary artery disease

Background Thrombocytosis and inflammation are vital elements in the pathogenesis of atherosclerosis. The platelet-to-lymphocyte ratio (PLR) is a novel biomarker that combines these parameters and has been shown to be associated with cardiovascular disease (CVD). This study aimed to determine whether PLR correlates with coronary artery disease (CAD) in high-risk patients, and if the relationship is affected by age. Methods Consecutive patients referred for coronary angiogram were evaluated (n = 822). with 608 patients demonstrating CAD, compared to 214 patients with normal coronary arteries. Patients were stratified into premature CAD (age < 55) and non-premature CAD (age ≥ 55). High and low PLR groups were defined as admission PLR in the highest (≥ 146.7) and lower two tertiles ( < 146.7) respectively. Multivariate logistic regression was undertaken to adjust for traditional cardiovascular risk factors. Results In univariate analysis, high PLR negatively correlated with premature CAD (OR 0.45, 95%CI 0.23–0.87, P = 0.017), while its association with CAD in older patients did not reach statistical significance (OR 1.32, 95%CI 0.89–1.97, P = 0.170). After adjustment for traditional risk factors, high PLR was significantly associated with increased CAD in older patients (OR 2.22, 95%CI 1.28–3.82, P = 0.004) but decreased premature CAD (OR 0.31, 95%CI 0.11–0.87, P = 0.026). Conclusions There is an age-related effect on the correlation between PLR and CAD. While high PLR was an independent marker of CAD in older high-risk patients, it was negatively correlated with premature CAD in younger patients. PLR is widely available and inexpensive, and could be used in highlighting patients at high risk for CAD.