Good Performance of Revised Scoring Systems in Predicting Clinical Outcomes of Aeromonas Bacteremia in the Emergency Department: A Retrospective Observational Study

Abstract

Background: Aeromonas species, Gram-negative, non-sporulating, facultative, and anaerobic bacilli, widely distributed in aquatic environments, derive various infections, including bacteremia. Most of these infections were opportunistic and found in patients with predisposing conditions. Among the infections, bacteremia remains with notable mortality, reported from 15% to 45%. However, predicting systems for assessing the mortality risk of this disease have yet to be investigated. We aimed to validate the performance of specific predictive scoring systems to assess the clinical outcomes of Aeromonas bacteremia and applied the revised systems to predict mortality risk.

Methods: A retrospective observational study reviewed patients with bacteremia caused by Aeromonas spp. based on at least one positive blood culture sample collected in the emergency department from January 2012 to December 2020. The outcome was in-hospital mortality. We used seven predictive scoring systems to predict the clinical outcome. According to the effectiveness in predicting mortality, we revised three of the seven predictive scoring systems by specific characteristics to refine their risk-predicting performances.

Results: We enrolled 165 patients with bacteremia caused by Aeromonas spp., including 121 males (73.3%) and 44 females (26.7%), with a mean age of 66.1 ± 14.9 years and an average length of hospital stay of 12.4 ± 10.9 days. The overall mortality rate was 32.7% (54/165). The non-survivors had significantly higher scores in MEDS (6.7 ± 4.2 vs. 12.2 ± 3.3, p < 0.001), NEWS (4.0 ± 2.8 vs. 5.3 ± 3.0, p = 0.008), and qSOFA (0.3 ± 0.6 vs. 0.6 ± 0.7, p = 0.007). Regarding mortality risk prediction, the MEDS demonstrated the best predictive power with AUC of ROC measured up to 0.834, followed by NEWS (0.626) and qSOFA (0.608). We revised the MEDS, NEWS, and qSOFA by hemoglobin and lactate. We found that the revised scores had better powerful performance, including 0.859, 0.767, and 0.691 of the AUC of ROC, if the revised MEDS ≥10, revised NEWS ≥8, and revised qSOFA ≥2, respectively.

Conclusions: MEDS, NEWS, and qSOFA were good tools for predicting outcomes in patients with Aeromonas spp. bacteremia. The revised MEDS, NEWS, and qSOFA demonstrated more powerful predicting performance than the original scoring systems. We suggested that patients with higher scores in revised MEDS (≥10), revised NEWS (≥8), and revised qSOFA (≥2) received early goal-directed therapy and appropriate broad-spectrum antibiotic treatment as early as possible to reduce mortality.

Keywords: Aeromonas; bacteremia; mortality risk; scoring systems; temperature.

Figure 1

The trend association between the seasonal average temperature and case numbers of bacteremia caused by Aeromonas spp., p = 0.008.

Figure 2

The trend association between the monthly average temperature and case numbers of bacteremia caused by Aeromonas spp., p = 0.005.

Figure 3

The AUC of ROC for the MEDS, NEWS, and qSOFA indicated 0.834, 0.626, and 0.608 to predict the mortality risks of patients with bacteremia caused by Aeromonas spp. (Panel (A)). The AUC of ROC for the revised MEDS, NEWS, and qSOFA indicated 0.859, 0.767, and 0.691 to predict the mortality risks of patients with bacteremia caused by Aeromonas spp. (Panel (B)). AUC, Area under the curve; MEDS, Mortality in Emergency Department Sepsis; NEWS, National Early Warning Score; qSOFA, quick Sepsis Related Organ Failure Assessment; ROC, Receiver operating characteristic curve.

Figure 4

The cumulative survival rates of patients with bacteremia caused by Aeromonas spp. were calculated to predict the 30-day mortality rate using Kaplan–Meier analyses. The cut-off point of the MEDS, NEWS, and qSOFA was 9, 5, and 1, respectively. MEDS, Mortality in Emergency Department Sepsis; NEWS, National Early Warning Score; qSOFA, quick Sequential Organ Failure Assessment.

Figure 5

The cumulative survival rates of patients with bacteremia caused by Aeromonas spp. were calculated to predict the 30-day mortality rate using Kaplan–Meier analyses. The cut-off point of the revised MEDS, NEWS, and qSOFA was 10, 8, and 2, respectively. MEDS, Mortality in Emergency Department Sepsis; NEWS, National Early Warning Score; qSOFA, quick Sequential Organ Failure Assessment.

Figure 6

The overall mortality case numbers of the MEDS, NEWS, and qSOFA were 52.6%, 41.2%, and 46.4% if the cut-off point was more than 9, 5, and 1. MEDS, Mortality in Emergency Department Sepsis; NEWS, National Early Warning Score; qSOFA, and quick Sequential Organ Failure Assessment.

Figure 7

The overall mortality case numbers of the revised MEDS, NEWS, and qSOFA were 57.8%, 56.0%, and 54.5% if the cut-off point was more than 10, 8, and 2. R-MEDS, Revised Mortality in Emergency Department Sepsis; R-NEWS, Revised National Early Warning Score; R-qSOFA, and Revised quick Sequential Organ Failure Assessment.