Correlation of shock index and modified shock index with the outcome of adult trauma patients: a prospective study of 9860 patients

Background: Triage at emergency department is performed to identify those patients who are relatively more serious and require immediate attention and treatment. Despite current methods of triage, trauma continues to be a leading cause of morbidity and mortality.

Aims: This study was to evaluate the predictive value of shock index (SI) and modified shock index (MSI) for hospital mortality among adult trauma patients.

Materials and methods: In this prospective longitudinal study, all adult patients who sustained trauma enrolled as per as inclusion/exclusion criteria. After the collection of data, SI and MSI were calculated accordingly. All parameters were again recorded hourly and calculations were done at six-hour intervals. Further, to achieve a value that can be analyzed, we determined threshold value for vital signs, which set the threshold values as heart rate at 120 beats per minute, systolic blood pressure at less than 90, and SI at cut-off 0.5-0.9 and MSI at less than 0.7 to more than 1.3.

Results: We analyzed 9860 adult trauma patients. Multivariate regression analysis demonstrated that heart rate more than 120 beats per minute, systolic blood pressure less than 90 mmHg, and diastolic blood pressure (DBP) less than 60 mmHg correlate with hospital stay and mortality rate. MSI <0.7 and >1.3 had higher odds of mortality as compared to other predictors.

Conclusions: MSI is an important marker for predicting the mortality rate and is significantly better than heart rate, systolic blood pressure, DBP and SI alone. Therefore, modified SI should be used in the triage of serious patients, including trauma patients in the emergency room.