Prognostic Value of Serum MMP9 in Predicting Mortality Among Elderly Patients with Sepsis: A Prospective Cohort Study

Background: Sepsis, recognized as a severe syndrome resulting from an uncontrolled inflammatory response, has emerged as a significant public health concern, and it has become a major public health issue, particularly among elderly individuals aged ≥ 65 years. Matrix Metalloproteinase-9 (MMP9), an enzyme belonging to the matrix metalloproteinase family, plays a pivotal role in the progression of various inflammatory and oncological diseases. Nevertheless, the influence of MMP9 on mortality prediction in elderly patients with sepsis remains ambiguous. Consequently, this study aimed to investigate the effect of serum MMP9 on 28-day mortality in elderly sepsis patients admitted to the intensive care unit (ICU). Methods: A total of 258 eligible elderly sepsis patients were included and divided into a discovery cohort and a validation cohort. Serum MMP9 and other biomarkers, such as interleukin-6 (IL-6) and lactate (LAC), were measured within 24 hours after admission, and clinical data, including 28-day survival status, SOFA scores, and APACHE II scores, were collected. Assessments were conducted using binary logistic regression and AUC analysis. A limitation of this study is the lack of prospective registration in a clinical trial registry. Results: The serum MMP9 levels in non-survivors were significantly lower than those in survivors. The AUC of MMP9 for predicting 28-day mortality ranged from 0.733 to 0.805 and increased to 0.855– 0.865 when combined with SOFA scores. Low concentrations of MMP9 were associated with reduced survival rates; MMP9 was negatively correlated with SOFA scores, APACHE II scores, and other biomarkers. MMP9, SOFA scores, APACHE II scores, and LAC were identified as independent predictors. Conclusion: Serum MMP9 at ICU admission is a significant predictor of 28-day mortality in elderly sepsis patients, providing references for early clinical treatment decisions. Keywords: sepsis, elderly patients, MMP9, mortality, risk prediction