Bacterial meningitis score accurately predicts which children are at low risk
Article Outline
- Nigrovic LE, Kuppermann N, Macias CG, Cannavino CR, Moro-Sutherland DM, Schremmer RD, et al. Clinical prediction rule for identifying children with cerebrospinal fluid pleocytosis at very low risk of bacterial meningitis. JAMA 2007;297:52-60
- References
- Copyright
Nigrovic LE, Kuppermann N, Macias CG, Cannavino CR, Moro-Sutherland DM, Schremmer RD, et al. Clinical prediction rule for identifying children with cerebrospinal fluid pleocytosis at very low risk of bacterial meningitis. JAMA 2007;297:52-60
Question Given the widespread use of pneumococcal conjugate vaccine, does the Bacterial Meningitis Score predict which children are at very low risk of bacterial meningitis?
Context Children with cerebrospinal fluid (CSF) pleocytosis are routinely admitted to the hospital and treated with parenteral antibiotics, although few have bacterial meningitis.
Design Multicenter, retrospective cohort study. The authors previously developed a clinical prediction rule, the Bacterial Meningitis Score, based on five predictors: positive CSF Gram stain, CSF absolute neutrophil count (ANC) of at least 1,000 cells/μL, CSF protein of at least 80 mg/dL, peripheral blood ANC of at least 10,000 cells/μL, and a history of seizure before or at the time of presentation. In the current study, patients lacking any of these predictors are classified as low risk.
Setting 20 US academic medical centers through the Pediatric Emergency Medicine Collaborative Research Committee of the American Academy of Pediatrics.
Participants All children aged 29 days to 19 years who presented to participating emergency departments between January 1, 2001, and June 30, 2004, with CSF pleocytosis (CSF white blood cells ≥10 cells/μL) and who had not received antibiotic treatment before lumbar puncture.
Outcome The sensitivity and negative predictive value of the Bacterial Meningitis Score.
Main Results Among 3295 patients with CSF pleocytosis, 121 (3.7%; 95% confidence interval [CI], 3.1%-4.4%) had bacterial meningitis and 3174 (96.3%; 95% CI, 95.5%- 96.9%) had aseptic meningitis. Of the 1714 patients categorized as very low risk for bacterial meningitis by the Bacterial Meningitis Score, only 2 had bacterial meningitis (sensitivity, 98.3%; 95% CI, 94.2%-99.8%; negative predictive value, 99.9%; 95% CI, 99.6%-100%), and both were younger than 2 months old. A total of 2518 patients (80%) with aseptic meningitis were hospitalized.
Conclusions This large multicenter study validates the Bacterial Meningitis Score prediction rule in the era of conjugate pneumococcal vaccine as an accurate decision support tool. The risk of bacterial meningitis is very low (0.1%) in patients with none of the criteria. The Bacterial Meningitis Score may be helpful to guide clinical decision making for the management of children presenting to emergency departments with CSF pleocytosis.
Commentary Meningitis is the most feared infectious entity among febrile infants and children presenting to emergency departments. Studies of clinical diagnosis have not identified reliable criteria for distinguishing between bacterial and viral etiologies.1 The decline in incidence of bacterial meningitis with the advent of effective vaccines against S. pneumoniae and H. influenzae b has heightened the potential value of such criteria in avoiding unnecessary admissions and treatment. Nigrovic, et al’s validation of their previously derived prediction rule is a welcome adjunct to clinical decision making. Their new retrospective study involves an acceptable simplification of the original rule which required calculation of a point score.2 A prospective clinical validation, although desirable, would be problematic in the post-vaccine era. In addition, this limitation is substantially mitigated by the objective nature of the predictors, with seizure being the only non-laboratory parameter. The sensitivity for detecting bacterial meningitis is 98%, identical to that observed originally. Given the low likelihood of bacterial meningitis prior to application of the rule, a patient with none of the predictors should have well less than a 1% probability of a positive CSF culture. Clinicians may be advised to be judicious in applying this rule to very young infants. In both studies, cases of missed bacterial meningitis were less than one year of age. Although Nigrovic, et al found a peripheral ANC ≥ 103 to be an independent predictor of bacterial source, a study of febrile infants less than 90 days old found an inverse relationship between peripheral WBC count and likelihood of bacterial meningitis, suggesting that young infants’ physiological responses to CNS infection may differ.3
References
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- . Development and validation of a multivariable predictive model to distinguish bacterial from aseptic meningitis in children in the post-haemophilus influenzae era. Pediatrics. 2002;110:712–719
- . Utility of the peripheral blood count for identifying sick young infants who need lumbar puncture. Ann Emerg Med. 2003;41:206–214
PII: S0022-3476(07)00369-1
doi:10.1016/j.jpeds.2007.04.020
© 2007 Mosby, Inc. All rights reserved.
