Shock Index-A Useful Noninvasive Marker Associated With Age-Specific Early Mortality in Children With Severe Sepsis and Septic Shock: Age-Specific Shock Index Cut-Offs

Abstract

Background: Aim of the study was to analyze the association of shock index (SI) from 0 to 6 hours with early mortality in severe sepsis/septic shock and to explore its age-specific cut-off values. To investigate association of change in SI over first 6 hours with early mortality. Methods: A prospective cohort study of children (<14 years) admitted in emergency department, tertiary care hospital with severe sepsis or septic shock, divided into 3 groups: group 1: 1 month to <1 year; group 2: 1 to <6 years; group 3: 6 to 12 years. Shock index (SI = heart rate/systolic blood pressure) measured at admission (X0) and hourly till 6 hours (X1-6). Primary outcome was death within 48 hours of admission. Area under receiver operating characteristic curves were constructed for SI (0-6). Optimal cut-offs of SI 0 and SI 6, maximizing both sensitivity and specificity were determined and positive and negative predictive values (PPV, NPV) were calculated. Results: From 2015 to 2016, 120 children were recruited. Septic shock was present at admission in 56.7% children. Early mortality was 50%. All hourly shock indices (SI 0-6) were higher among nonsurvivors in group 2 ( P ≤ .03) and group 3 ( P < .001). In group 1, SI after 2 hours was higher in nonsurvivors ( P 2-6: ≤ .02). Area under receiver operating characteristic curves (95% CI) for SI at 0 hour was 0.72 (0.5-0.9), 0.66 (0.5-0.8), and 0.77 (0.6-0.9) and at 6 hours was 0.8 (0.6-1), 0.75 (0.6-0.9), and 0.8 (0.7-1) in 3 groups. The cut-off values of SI 0 (sensitivity; specificity; PPV; NPV) in 3 groups: 1.98 (77; 75; 67; 83), 1.50 (65; 65; 68; 63), and 1.25 (90; 67; 77; 83) and SI6: 1.66 (85; 80; 73; 89), 1.36 (73; 70; 73; 70), and 1.30 (74; 73; 78; 69). Improvement of SI over 6 hours was associated with better outcome. Children with higher SI at both time points had higher mortality than those with SI score below the cut-offs ( P = .001). Conclusions: Age-specific SI cut-off values may identify children at high risk of early mortality in severe sepsis/septic shock and allow for better targeted management.