Shock index in a rural setting: Can it predict mortality? A retrospective audit in two central hospitals in Limpopo Province, South Africa

Background. Shock index is (SI) obtained by dividing heart rate by systolic blood pressure (SBP). Previous studies have shown that SI >0.9 is a predictor of mortality and of a need for blood transfusion in trauma patients. Objective. To determine whether SI can predict mortality and the need for blood transfusion in a rural South African provincial referral hospital cohort. Methods. A retrospective observational cross-sectional study of trauma patients with injury severity score (ISS)>15 in two central hospitals in a rural province was undertaken using data from January 2018 to December 2020. Data collection included demographics, heart rate, blood pressure, SI and modified shock index (MSI) at the time of admission to the emergency department. Univariate and multivariate analyses were performed to identify whether SI predicted death or need for transfusion. Results. The cohort comprised 324 patients. Only emergency department SI and MSI were calculated. In multivariate analysis, χ2 tests showed that SI was a good predictor of mortality (p<0.011) and need for blood transfusion (p<0.001). SI with area under curve 0.673 is a fair predictor of mortality. Student’s t-test showed that patients who died had lower mean SI than those who survived, with a mean difference of –2.78 (p=0.006). In multivariate analysis, severe SI predicted the need for blood transfusion (p=0.032). Conclusion. SI is a useful predictor of mortality and the need for blood transfusion in this cohort of referred patients to two central facilities in a rural province. There is likely an impact from resuscitation prior to arrival at the central hospitals.