SIRS is Rarely Sepsis

You already knew this – but that hasn’t stopped your hospital from purchasing the “Sepsis Alert” tool for your electronic health record.  Now, you and your nurses get blasted with computerized interruptions every time a patient is tachycardic and has an elevated WBC count.  And, you ignore it – because it’s 1) wrong, or 2) you placed a central line and admitted the patient to the ICU half an hour ago.

But, just how often do these sepsis alerts, based on systemic inflammatory response criteria, fire erroneously?  That is the question asked by this group from Harbor-UCLA and UC Davis.  Using the National Hospital Ambulatory Medical Care Survey from 2007 to 2010, these authors attempted to estimate the frequency of true infection in the setting of SIRS.  Unfortunately, while the NHAMCS set now includes vital signs obtained at triage, it does not include results of tests, such as the WBC.  Therefore, these authors – and this is where the study breaks down a bit – were required to mathematically conjure up a range of estimates for the frequency with which patients would meet the WBC criterion for SIRS.  Based on minimum and maximum estimates, the percentage of Emergency Department visits estimated to have SIRS ranged from 9.7% to 26.0%, and the authors ultimately split the difference at 17.8% for their analysis.

Based on their estimate, there were approximately 66 million visits to Emergency Departments meeting SIRS criteria, and the largest cohort of eventual diagnoses for these patients was indeed infection – but this constituted a mere 26% of all SIRS.  The remaining diagnoses were scattered among trauma, mental disorders, respiratory diseases, and other non-specific, organ-system dysfunction, catch-all ICD-9 codes.  While the interruptions and low specificity of SIRS alert tools are the obvious problem addressed by this study, the other implication is the troubling scope of the problem:  after trauma and infection are excluded, there are approximately 42 million other ED visits that may erroneously trip institutional protocols, costly unnecessary testing, and additional resource utilization targeting sepsis.

This is the sort of decision-support that simply doesn’t add any proven value, and another venue of encroachment into efficient and effective care.

“Epidemiology of the Systemic Inflammatory Response Syndrome (SIRS) in the Emergency Department”
http://www.ncbi.nlm.nih.gov/pubmed/24868313