Predicting bacterial vs viral meningitis

Short Attention Span Summary

What did the study show?
The Bacterial Meningitis Score accurately predicts which children have bacterial vs. aseptic meningitis, but how does it perform in adults?  It did well in this study, with sensitivity 100% and NPV 100%.  Before we get too eager, the 95% confidence interval for sensitivity was 40-100%.  For stats neophytes - that's a bit wide.  The fact is, though this study was a retrospective review of cases going back a decade, there weren't that many people with meningitis: 441 to be exact, 4 (1%) of whom had bacterial meningitis.

What do I do with this information?
We have to decide which patients to admit and treat with antibiotics until we have culture results.  My take is to use the Bacterial Meningitis Score to frame your thinking and then err on the cautious side if there is any doubt.  For example, if there are only 999 CSF neutrophils and no other positive variables, your patient would be classified as "Aseptic meningitis very likely."  But are you going to send someone home with 999 PMNs in their CSF?  Besides, many of these patients have a splitting headache and may benefit from IV pain control.  So use this score in kids and adults, but also use common sense.  Journal Watch had a similar take on this article.

Spoon Feed
You can apply the Bacterial Meningitis Score to adults as well as kids, but do so with caution and common sense.


Abstract

Am J Emerg Med. 2016 Jul;34(7):1265-7. doi: 10.1016/j.ajem.2016.04.003. Epub 2016 Apr 7.

Validation of the bacterial meningitis score in adults presenting to the ED with meningitis.

McArthur R1, Edlow JA2, Nigrovic LE3.

Author information:

1Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, MA; Department of Emergency Medicine, St. Luke's Hospital, New Bedford, MA. Electronic address: rmcarthu@bidmc.harvard.edu.

2Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, MA.

3Division of Emergency Medicine, Department of Pediatrics, Boston Children's Hospital, Boston, MA.

Abstract

OBJECTIVES:

The Bacterial Meningitis Score classifies children with meningitis and none of the following high-risk predictors at very low risk for bacterial meningitis: positive cerebrospinal fluid (CSF) Gram stain, CSF protein ≥80mg/dL, CSF absolute neutrophil count (ANC) ≥1000 cells/mm(3), peripheral ANC ≥10,000 cells/mm(3), and seizure at or prior to presentation. Although extensively validated in children, the Bacterial Meningitis Score has not been rigorously evaluated in adults.

METHODS:

We performed a single-center cross-sectional retrospective study of adults presenting to the emergency department between 2003 and 2013 with meningitis (defined by CSF white blood cell count ≥10 cells/mm(3)). We defined a case of bacterial meningitis with either a positive CSF or blood culture. We report the performance of the Bacterial Meningitis Score in the study population.

RESULTS:

We identified 441 eligible patients of which, 4 (1%) had bacterial meningitis. The Bacterial Meningitis Score had a sensitivity of 100% [95% confidence interval (CI) 40%-100%], specificity 51% (95% CI, 46%-56%) and negative predictive value of 100% (95% CI, 98%-100%). None of the low risk adults had bacterial meningitis. If Bacterial Meningitis Score had been applied prospectively, the hospital admission rate would have dropped from 84% to 49% without missing any patients with bacterial meningitis.

CONCLUSIONS:

The Bacterial Meningitis Score accurately identified patients at low risk for bacterial meningitis and could assist clinical decision-making for adults with meningitis.

Copyright © 2016 Elsevier Inc. All rights reserved.

PMID: 27139257 [PubMed - in process]