A large cohort study out of Denmark examining over 17,000 ER visits by adults determined that the absence of all three criteria fever, elevated CRP and SIRS criteria had a 99.5% negative predictive value for excluding bacteremia.
Fever, elevated CRP level, or SIRS criteria alone did not predict bacteremia, but when all three parameters were negative, bacteremia was present in fewer than 1% of patients.
Researchers assessed the value of temperature, C-reactive protein (CRP) level, and systemic inflammatory response syndrome (SIRS) criteria for early identification of bacteremia in a population-based cohort study of more than 17,000 visits by adults to an emergency department in Denmark over a 2-year period.
Systemic Inflammatory Response Criteria
Temperature, although one of the SIRS criteria, was analyzed separately as it is often the decisive factor for drawing blood cultures. Bacteremia was defined as a positive blood culture within the first 48 hours, elevated CRP was defined as a level >10 mg/dL, and SIRS was considered present if two of four criteria were met.
The SIRS criteria are temperature >38oC or <36oC, respiratory rate >20 breaths per minute, heart rate >90 beats per minute, and leukocyte count >12K or <4K
Blood cultures were drawn for 46% of patients and were positive in 7.6% (corresponding to 3.5% of all patients). The most frequent pathogens were Escherichia coli (30%) and Streptococcus pneumoniae (13%); patients with these species were more likely to have elevated CRP and SIRS. Among bacteremic patients, 34% were normothermic on arrival, 33% had CRP <10 mg/dL, and 28% had fewer than two SIRS criteria; however, only 5% had the combination of normal temperature, CRP <100 mg/L, and fewer than two SIRS criteria.
Lindvig KP et al. 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? Scand J Trauma Resusc Emerg Med. 2014 Jul 15; 22:39. Link.