Clinical factors associated with mortality in septic shock

Introduction

Septic shock (SS) is a disease associated with high mortality worldwide. In Brazil, mortality in SS reaches 60%. The aim of our study was to identify clinical variables easily accessed in the presentation of SS and their correlation with mortality.

Methods

Between January 2003 and December 2004, all patients with SS criteria according to the ACCP/SCCM were included in this observational study. At the time of SS diagnosis the following variables were collected: age, gender, heart rate (HR) and mean arterial pressure (MAP). On the ICU admission day the APACHE II and SOFA scores were calculated. Data were retrieved from the patient chart by one of the investigators, then transferred to STATA version 9.0 software, where all analyses were run. All patients were followed until ICU discharge or death.

Results

During the period of study, there were 794 admissions to the ICU, of whom 239 (30%) presented SS. Sixty-seven percent were male, mean age was 57.0 (SD = 17.7) years, mean HR was 108 (SD = 26.3) bpm, and mean MAP was 64.5 (SD = 21.2) mmHg. The mean APACHE II score was 23.3 (SD = 8.6) and the mean SOFA score was 9.7 (SD = 3.2). The ICU mortality rate was 66.5%. In the analysis of the prevalence of mortality and its crude association with independent variables, age and gender show no association. Patients with HR above 108 bpm presented a mortality OR of 1.78 (0.98–3.24) compared with those patients with HR equal to or less than 108 bpm (P < 0.05). An APACHE II score greater than 24 points was associated with a mortality OR of 2.91 (1.52–5.78) compared with those patients with a score equal to or less than 24 (P < 0.001). A SOFA score greater than 8 points was associated with a mortality OR of 1.89 (1.04–3.42), compared with patients with values equal to or less than 8. The analysis of MAP demonstrated a trend to a lower mortality, in association with a higher level.

Conclusion

Our study confirmed, as previously demonstrated, that a HR less than 110 bpm at SS presentation is associated with low mortality, as well a higher level of MAP. The severity of illness (APACHE II score > 24 points) is indicative of high-risk mortality; multiple organ dysfunction (SOFA score > 8 points), and a worse outcome.