How do bacteraemic patients present to the emergency department and what is the diagnostic validity of the clinical parameters; temperature, C-reactive protein and systemic inflammatory response syndrome?

Abstract

Objective: Although blood cultures are often ordered based on the presence of fever, it is a clinical challenge to identify patients eligible for blood cultures. Our aim was to evaluate the diagnostic value of temperature, C-reactive-protein (CRP), and Systemic Inflammatory Response Syndrome (SIRS) to identify bacteraemic patients in the Medical Emergency Department (MED).

Methods: A population-based cohort study including all adult patients at the MED at Odense University Hospital between August 1st 2009 - August 31st 2011.

Results: 11,988 patients were admitted to the MED within the study period. Blood cultures were performed on 5,499 (45.9%) patients within 2 days of arrival, of which 418 (7.6%) patients were diagnosed with bacteraemia. This corresponded to 3.5% of all patients. 34.1% of the bacteraemic patients had a normal rectal temperature (36.0°-38.0 °C) recorded at arrival, 32.6% had a CRP < 100 mg/L and 28.0% did not fulfil the SIRS criteria.For a temperature cut-point of >38.0 °C sensitivity was 0.64 (95% CI 0.59-0.69) and specificity was 0.81 (0.80-0.82) to identify bacteraemic patients.

Conclusion: One third of the acute medical bacteraemic patients had a normal temperature at arrival to the MED. A normal temperature combined with a CRP < 100 mg/L and no SIRS criteria, ruled out bacteraemia.

Figure 1

Receiver operating curve (ROC) for temperature as a diagnostic test for bacteraemia in the medical emergency department. The analysed cut-points are 36°C–41°C. The figure shows that the ROC for temperature has an area under the curve of 0.75.

Figure 2

Receiver operating curve (ROC) for C-reactive protein as a diagnostic test for bacteraemia in the medical emergency department. The analysed cut-points are CRP 10–350 mg/dL. The figure shows that the ROC for CRP has an area under the curve of 0.70.

Figure 3

Receiver operating curve (ROC) for systemic inflammatory response syndrome as a diagnostic test for bacteraemia in the medical emergency department. The analysed cut-points are SIRS criteria 0–4. The figure shows that the ROC for SIRS has an area under the curve of 0.76.