V. Polcz1, L. Podolsky2, O. Sizar1, A. Farooq1, M. Bukur1, I. Puente1, F. Habib1,2 1Broward Health Medical Center,Trauma,Ft Lauderdale, FL, USA 2Florida International University,Surgery,Ft Lauderdale, FL, USA
Introduction:
Fever remains the most common sign that prompts the work-up for a possible infectious etiology in critically injured trauma patients admitted to the ICU. Yet, the very definition of fever is highly variable, and the test characteristics of the various cut-offs used have not been clearly defined. An accurate cut-off would allow for more precise and cost-effective management of the febrile trauma patient.
Methods:
Charts for 621 trauma patients at our urban Level I trauma Center were retrospectively evaluated for fever and culture results. The maximum oral temperature during the 24 hour period prior to obtaining culture samples was used. Temperatures were correlated with positive or negative culture results to determine sensitivity, specificity, positive and negative predictive values, positive and negative likelihood ratios, and area under the curve.
Results:
Sensitivity and specificity were calculated using using cut-off values of 100.4 F, 101 F, and 101.5 F. All data points are shown in Table 1. Recierver Operator Curve cut-offs identified 99.75 F as the temperature with the best test characteristics. Sensitivity showed an inverse relationship with temperature. 99.75 degrees exhibited a maximum value of 75.30% (CI: 70.27-79.88), with 101.5 exhibiting the minimum value of 25% (CI: 20.87-29.50). Specificity had a direct relationship to temperature, with 99.75 having a minimum specificity of 59.46% (CI: 51.00-61.00) and 101.5 having a maximum specificity of 92.96% (CI: 88.65-96.00). Positive likelihood ratio (LR) had a lowest value of 1.86 (CI:1.51-2.28) at the lowest temperature of 99.75, and the highest value of 3.35 (CI 2.12-5.95) at 101.5. Negative LR was also lowest at 99.75 with a value of 0.42 (CI: 0.33-0.52), and highest 101.5 with a value of 0.81 (CI: 0.75-0.86). Positive predictive value (PPV) was lowest at a temperature of 99.75 at 80.46% (CI: 75.57-84.74) and highest at a temperature of 101.5 at 39.29% (CI: 35.00-43.70). Negative predictive value (NPV) was highest at 99.75 with a value of 52.07% (CI: 44.27-59.80) and lowest at 101.5 with a value of 39.29% (CI: 35.00-43.70). AUC was inversely related to temperature with a maximum value of 0.32 (CI 0.690-0.774) at 99.75 and a minimum value of 0.498 (CI: 0.450-0.546) for 101.5.
Conclusion
These results suggest that none of the current cut-offs used to define fever accurately predict an infectious etiology in febrile patients. While a temperature of 99.75 demonstrated the best test characteristics, none of the commonly accepted standards of fever showed a strong correlation to culture results. Further research is warranted in order to identify biomarkers that accurately identify the presence of infectious processes in trauma patients.
