945. Multi-Center Validation Of A Clinical Decision Rule To Distinguish Lyme From Aseptic Meningitis
Session: Poster Abstract Session: Central Nervous System Infections in Children
Saturday, October 22, 2011
Room: Poster Hall B1

The “Rule of 7’s,” a Lyme meningitis clinical decision rule, classifies children at low risk for Lyme meningitis when each of the following three criteria are met: < 7 days of headache, < 70% cerebrospinal (CSF) mononuclear cells, and absence of 7th or other cranial nerve palsy. 


Our objective is to test the performance of the “Rule of 7’s” in a multi-center cohort of children with CSF pleocytosis.  We performed a retrospective cohort study of children evaluated at one of three emergency departments located in Lyme endemic areas with CSF pleocytosis who had Lyme serology obtained. Lyme meningitis was defined using the Centers for Disease Control and Prevention criteria [either positive Lyme serology or an erythema migrans (EM) rash].  We calculated the performance of the “Rule of 7’s” in our overall study population and in children without physician-documented EM. 


We identified 423 children of which 117 [28%, 95% confidence interval (CI) 24-32%] had Lyme meningitis and 0 (95% CI 0 - 1%) had bacterial meningitis.  Of the 130 classified at low-risk, 5 had Lyme meningitis [sensitivity 112/117 (96%, 95% CI 90–99%), specificity 125/302 (41%, 95% CI 36-47%), negative predictive value 125/130 (96%, 95% CI 91-98%)].  In the 390 children without EM, 3 of the 127 low-risk patients had Lyme meningitis (2%, 95% CI 0-7%).


Patients classified as low risk by the “Rule of 7’s” were unlikely to have Lyme meningitis and might be managed as outpatients while awaiting results of Lyme serology.   

Subject Category: P. Pediatric and perinatal infections

Cohn Keri, MD DTMH1, Amy Thompson, MD2, Samir Shah, MD, MSCE3,4, Elizabeth Hines, BA4, Todd Lyons, MD5, Elizabeth Welsh, BA6 and Lise Nigrovic, MD, MPH7, (1)Division of Infectious Diseases, Childrens Hospital Boston, Boston, MA, (2)Emergency Medicine, Nemours/ A.I. duPont Hospital for Children, Wilmington, DE, (3)University of Pennsylvania, Philadelphia, PA, (4) Center for Pediatric Clinical Effectiveness, Children's Hospital of Philadelphia, Philadelphia, PA, (5)Pediatrics (Medicine), Childrens Hospital Boston, Boston, MA, (6)4Departments of Pediatrics and Biostatistics and Epidemiology, University of Pennsylvania/ Childrens Hospital of Philadelphia, Philadelphia, PA, (7)Division of Emergency Medicine, Childrens Hospital Boston, Boston, MA


C. Keri, None

A. Thompson, None

S. Shah, None

E. Hines, None

T. Lyons, None

E. Welsh, None

L. Nigrovic, None

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.