Abstract
Dilated cardiomyopathy is characterized by progressive left ventricular dilation and impaired systolic function, with inflammation recognized as a key contributor to disease onset and adverse outcomes. C-reactive protein reflects systemic biochemical inflammation, whereas Delta Neutrophil Index represents the circulating immature neutrophil fraction and provides a cellular dimension of inflammatory burden. The combined diagnostic and prognostic value of these two biomarkers in dilated cardiomyopathy has not been adequately explored. This retrospective study included one hundred and fifty patients with dilated cardiomyopathy and one hundred and fifty age-, diabetes-, and hypertension-matched controls. Demographic, laboratory, and echocardiographic measurements were analyzed. The diagnostic and prognostic performances of C-reactive protein, Delta Neutrophil Index, and their combined model were assessed using logistic regression, receiver operating characteristic curve analysis, reclassification metrics, calibration testing, and decision curve analysis. Additional analyses were performed for patients with left ventricular ejection fraction below twenty percent, and mortality predictors were examined within the dilated cardiomyopathy cohort. Both C-reactive protein and Delta Neutrophil Index levels were significantly higher in patients with dilated cardiomyopathy than in controls and were further elevated in those with severely reduced ejection fraction. Delta Neutrophil Index remained independently associated with severe left ventricular dysfunction (ejection fraction ≤ 20%) in multivariable analysis (odds ratio 2.51). Each biomarker showed an independent association with the presence of dilated cardiomyopathy, and their combined model achieved the highest diagnostic accuracy. In receiver operating characteristic analysis, the area under the curve was 0.895 for Delta Neutrophil Index, 0.691 for C-reactive protein, and increased to 0.920 for the combined model, with a sensitivity of 81.3% and specificity of 92.0%. Delta Neutrophil Index was independently associated with severe left ventricular dysfunction and mortality, while C-reactive protein, age, ejection fraction, urea, and sodium also contributed to mortality risk. Delta Neutrophil Index was independently associated with mortality (odds ratio 2.51), while C-reactive protein, age, ejection fraction, urea, and sodium also contributed to mortality risk. The combined model provided significant improvement in risk reclassification and demonstrated superior calibration and greater net clinical benefit across a wide range of decision thresholds. C-reactive protein and Delta Neutrophil Index offer complementary diagnostic and prognostic information in dilated cardiomyopathy. Their combined use enhances diagnostic discrimination, strengthens risk stratification, and improves identification of patients at high risk for severe ventricular dysfunction and mortality. Incorporation of these accessible biomarkers into clinical evaluation may support earlier recognition and more tailored management of high-risk individuals.