The Platelet-to-Hemoglobin Ratio as a Prognostic Marker in Patients with Diabetes Mellitus and Acute Coronary Syndrome

<b>Background:</b> The platelet-to-hemoglobin ratio (PHR) has emerged as a potential prognostic marker in various cardiovascular contexts, but its role in acute coronary syndrome (ACS), particularly among patients with diabetes mellitus (DM), remains unclear. <b>Methods:</b> In this retrospective cohort study, 843 ACS patients admitted to the 2nd Cardiology Department at Hippokration Hospital of Thessaloniki, Greece, between 2017 and 2023 were evaluated. PHR was calculated from admission complete blood counts. The primary endpoint was all-cause mortality during a median follow-up of 25 months. Multivariate logistic and Cox regression analyses, receiver operating characteristic (ROC) curves, Kaplan-Meier survival analyses, and restricted cubic spline (RCS) models were employed, with subgroup analyses by DM status. <b>Results:</b> Higher PHR was independently associated with increased mortality in the overall cohort (adjusted hazard ratio [aHR] 1.35, <i>p</i> < 0.001). This association showed stronger predictive value in DM patients, reflected in both a higher aHR (1.52 vs. 1.36 in non-DM patients, <i>p</i> < 0.001 and <i>p</i> = 0.018, respectively) and superior discriminative performance on ROC analysis (AUC 0.707 vs. 0.600 overall, <i>p</i> = 0.0006). Kaplan-Meier analysis confirmed poorer survival in high-PHR groups, especially in DM patients. RCS analysis revealed a J-shaped relationship, with risk increasing markedly beyond PHR values of 2.2. <b>Conclusions:</b> PHR is an independent predictor of long-term mortality in ACS, with greater prognostic significance in DM patients. Its simplicity, low cost, and availability from routine blood tests make it a promising tool for risk stratification in ACS.