[Correlation between shock index and severity of septic shock and its prognostic value]

To discuss the correlation between shock index (SI) and severity and the values to forecast the prognosis in patients with septic shock.

127 patients with septic shock admitted to intensive care unit (ICU) of Zhejiang Provincial People's Hospital from January 1st, 2016 to October 31st, 2017 were enrolled, and they were divided into survival group and death group according to the outcomes after 28-day hospitalized. The vital signs, laboratory indexes, acute physiology and chronic health evaluation II (APACHE II), sequential organ failure assessment (SOFA), lactate clearance rate (LCR) of 3 hours after fluid resuscitation, and shock index on admission (SI₁) and shock index of 3 hours after fluid resuscitation (SI₂) were compared between the two groups. The correlation among SI and APACHE II, SOFA, LCR was analyzed. The receiver operating characteristic curve (ROC) was drawn to evaluate the prognostic value of SI in patients with septic shock.

A total of 127 patients were included, 52 in survival group (40.9%) and 75 in death group (59.1%). The SI₁, SI₂, APACHE II and SOFA in the death group were significantly higher than those in the survival group (SI₁: 1.62±0.46 vs. 1.35±0.32, SI₂: 1.36±0.24 vs. 0.93±0.15, APACHE II: 17.5±4.0 vs. 13.6±3.5,SOFA: 9.5±2.3 vs. 6.3±1.5), and LCR was significantly lower than that in the survival group [(14.4±5.2)% vs. (28.6±8.6)%], with statistically significant differences (all P < 0.01). The correlation analysis showed that SI₁ was significantly positively correlated with APACHE II (r = 0.458, P = 0.000) and SOFA (r = 0.535, P = 0.000), SI₂ was also significantly positively correlated with APACHE II (r = 0.624, P = 0.000) and SOFA (r = 0.656, P = 0.000), while SI₁ and SI₂ were significantly negatively correlated with LCR (r values were -0.348, -0.435, both P = 0.000), and the SI₂ were more remarkable. ROC curve analysis showed that the area under ROC curve (AUC) of SI₁ for predicting the prognosis of septic shock was 0.720 [95% confidence interval (95%CI) = 0.620-0.831, P < 0.05]; when SI₁ = 1.68, the sensitivity, specificity, Yoden index, positive predictive value and negative predictive value were 79.5%, 65.6%, 0.451, 0.759 and 0.636, respectively. The AUC of the SI₂ to predict prognosis of septic shock was 0.826 (95%CI = 0.739-0.826, P < 0.05); when SI₂ = 1.37, the sensitivity, specificity, Yoden index, positive predictive value and negative predictive value were 85.7%, 87.6%, 0.733, 0.893 and 0.902, respectively.

Compared with SI₁, SI₂ was more correlated with the severity in patients with septic shock and it had more values to predict prognosis.