Impact of Platelet-to-HDL-Cholesterol Ratio on Long-Term Mortality in Coronary Artery Disease Patients with or Without Type 2 Diabetes: Insights from a Chinese Multicenter Cohort

Background: Inflammation contributes to the initiation and advancement of both coronary atherosclerosis and type 2 diabetes mellitus (T2DM). Recent evidence has underscored the platelet-to-HDL-cholesterol ratio (PHR) as a promising inflammatory biomarker closely linked to the severity of coronary artery disease (CAD). Nevertheless, the risk of adverse clinical outcomes remains unclear among CAD patients with varying PHR levels and glycemic status. Methods: A total of 56,316 CAD patients were enrolled, primarily focusing on mortality outcomes. Patients were categorized into four subgroups based on median baseline PHR values and glycemic status: lower PHR (PHR-L) and higher PHR (PHR-H) with or without T2DM. Cox proportional hazard model and subgroup analysis were employed to investigate the association between PHR and glycemic status with mortality. Results: Over a median 5.32-year follow-up, 8909 (15.8%) patients experienced all-cause mortality, with 3873 (6.9%) deaths attributed to cardiovascular causes. Compared to individuals in PHR-L/non-DM, those in PHR-H/non-DM, PHR-L/DM and PHR-H/DM groups exhibited a higher risk of all-cause death [adjusted hazard ratio (HR) 1.12, 95% confidence interval (CI) 1.06– 1.18; HR 1.21, 95% CI 1.14– 1.29; HR 1.43, 95% CI 1.34– 1.52, respectively], as well as cardiac mortality [HR 1.19, 95% CI 1.08– 1.30; HR 1.58, 95% CI 1.44– 1.74; HR 1.89, 95% CI 1.72– 2.07, respectively]. Cox proportional hazard model also revealed the highest mortality risk among patients in PHR-H/DM compared to other groups (P < 0.05). Restricted cubic spline regression analysis revealed a positive linear association between PHR and all-cause as well as cardiac mortality (P for non-linearity > 0.05) after adjustment. Additionally, subgroup analysis indicated consistent effects on cardiac mortality within diverse subsets. Conclusion: In this real-world observational cohort analysis, elevated PHR levels joint with T2DM were related to adverse long-term clinical outcomes in CAD patients. PHR levels may serve as a valuable tool for identifying high-risk individuals within this specific group. Trial Registration: The Cardiorenal ImprovemeNt II registry NCT05050877. Keywords: platelet-to-HDL-cholesterol ratio, coronary artery disease, diabetes, all-cause mortality, cardiovascular mortality