Comparative Evaluation of Shock Index and Modified Shock Index in Predicting Outcomes of Sepsis Patients with and without Comorbidities: A Prospective Observational Study from a Tertiary Care Emergency Department

BACKGROUND: Sepsis is a life-threatening medical emergency requiring early identification and prompt intervention. Simple bedside hemodynamic indices such as shock index (SI) and Modified SI (MSI) have been proposed as early predictors of severity and outcome in sepsis. OBJECTIVES: The objective of the study was to compare the prognostic utility of SI and MSI in predicting severity and outcomes of sepsis among patients with and without comorbidities presenting to the emergency department (ED). MATERIALS AND METHODS: This prospective observational analytical study was conducted over 12 months in the ED of a Tertiary Care Teaching Hospital in Tamil Nadu. Fifty adult patients (18-65 years) presenting with sepsis (quick sequential organ failure assessment ≥2) were enrolled and divided into two groups: patients with comorbidities (Group A, n = 25) and without comorbidities (Group B, n = 25). SI (heart rate [HR]/systolic blood pressure) and MSI (HR/mean arterial pressure) were calculated at presentation. Primary outcomes included the need for mechanical ventilation. Receiver operating characteristic curve analysis was performed to assess predictive validity. RESULTS: Mortality was higher among patients with comorbidities (64%) compared to those without comorbidities (36%). Baseline vital parameters were comparable between groups (P > 0.05). Mean SI and MSI did not differ significantly between survivors and nonsurvivors. However, SI ≥1 was associated with higher mortality, particularly in patients with comorbidities. MSI ≤0.7 and ≥1.3 was associated with 100% mortality in both groups. In patients with comorbidities, MSI demonstrated fair predictive ability for the need for mechanical ventilation at 24 h (area under the curve 0.76; 95% confidence interval: 0.27-0.93), outperforming SI. CONCLUSION: Both SI and MSI are useful bedside tools for early risk stratification in sepsis. MSI demonstrated superior predictive performance compared to SI, particularly in patients with comorbidities.