Prediction of median survival time in sepsis patients by the SOFA score combined with different predictors

Abstract

Background: Sepsis is the leading cause of intensive care unit (ICU) admission. The purpose of this study was to explore the prognostic value of the Sequential Organ Failure Assessment (SOFA) score, the Acute Physiological and Chronic Health Evaluation II (APACHE II) score, and procalcitonin (PCT), albumin (ALB), and lactate (LAC) levels in patients with sepsis.

Methods: Consecutive adult patients with suspected or documented sepsis at ICU admission were recruited. Their basic vital signs and related auxiliary examinations to determine their PCT and ALB levels and APACHE II score were recorded at ICU admission, and their LAC levels and SOFA scores were recorded for one week after admission. The influence of these variables on hospital mortality was evaluated. Logistic regression was used to derive the Sepsis Hospital Mortality Score (SHMS), a prediction equation describing the relationship between predictors and hospital mortality. The median survival time was calculated by the Kaplan-Meier method. In the validation group, the kappa value was calculated to evaluate the stability of the derived formula.

Results: This study included 894 sepsis patients admitted to 18 ICUs in 16 tertiary hospitals. Patients were randomly assigned to an experimental group (626 cases) and validation group (258 cases). In addition, a nonsurvival group (248 patients) of the experimental group was established according to the outcome at the time of discharge. The hospital mortality rate in the experimental group was 39.6% (248/626). Univariate and multivariate regression analyses revealed that the APACHE II score (odds ratio [OR] = 1.178), △SOFA (OR = 1.186), △LAC (OR = 1.157), and SOFA mean score (OR = 1.086) were independently associated with hospital mortality. The SHMS was calculated as logit(p) = 4.715 - (0.164 × APACHE II) - (0.171 × △SOFA) - (0.145 × △LAC) - (0.082 × SOFA mean). A receiver operating characteristic curve was constructed to further investigate the accuracy of the SHMS, with an area under the curve of 0.851 (95% confidence interval [CI] 0.821-0.882; p < 0.001) for hospital mortality. In the low-risk group and high-risk groups, the corresponding median survival times were 15 days and 11 days, respectively.

Conclusion: The APACHE II score, △SOFA, △LAC and SOFA mean score were independently associated with hospital mortality in sepsis patients and accurately predicted the hospital mortality rate and median survival time. Data on the median survival time in sepsis patients could be provided to clinicians to assist in the rational use of limited medical resources by facilitating prudent resource allocation.

Trial registration: ChiCTR-ECH-13003934, retrospectively registered on August 03, 2013.

Keywords: APACHE II; Acute Physiological and Chronic Health Evaluation II; Lactate; Mortality; SOFA; Sepsis; Sequential Organ Failure Assessment.

Figure 1.

Inclusion of patients for analysis of the association between different predictors and mortality at hospital discharge between January 2014 to August 2015. CPR Cardiopulmonary Resuscitation

Figure 2.

Changes in Sequential Organ Failure Assessment (SOFA) scores on the first, third and seventh day of admission in the nonsurvival group and the survival group. D1 day 1, D2 day 2, D3 day 3

Figure 3.

Prognostic value of the new risk factor, Sepsis Hospital Mortality Score (SHMS), for hospital mortality. (a, b) The value of SHMS in the survival and nonsurvival groups; (c, d) comparison of receiver operating characteristic (ROC) analysis of the Acute Physiology and Chronic Health Evaluation II (APACHE II) score, △LAC2, △SOFA2, mean Sequential Organ Failure Assessment (SOFA) score and SHMS for the prediction of hospital mortality of patients with sepsis. LAC lactate

Figure 4.

Kaplan–Meier plot showing survival according to increased sepsis hospital mortality score in the experimental group. (a) Kaplan–Meier plot showing the sepsis-related hospital mortality in the low-risk group: 0.001–0.332 and high-risk group: 0.332–0.996. The median survival times of the two groups were 15 days and 11 days, respectively (log-rank = 0.000). (b) Kaplan–Meier plot showing the sepsis-related hospital mortality in the low-risk group: 0.001–0.332, moderate-risk group: 0.332–0.800, and high-risk group: 0.332–0.996. The median survival times of the three groups was 15 days, 13 days, and 5 days, respectively (log-rank = 0.000)