Validation Of The Rule Of 7'S For Identifying Children At Low-Risk For Lyme Meningitis

Background:The Rule of 7's classifies children as low-risk for Lyme meningitis with the absence of the following: >= 7 days of headache, any cranial neuritis or >= 70% cerebrospinal fluid mononuclear cells. We sought to broadly validate this clinical prediction rule in children with meningitis undergoing evaluation for Lyme disease.Methods:We performed a patient-level data meta-analysis of 2 prospective and 2 retrospective cohorts of children <= 21 years of age with cerebrospinal fluid pleocytosis who underwent evaluation for Lyme disease. We defined a case of Lyme meningitis with a positive 2-tier serology result (positive or equivocal first-tier enzyme immunoassay followed by a positive supplemental immunoblot). We applied the Rule of 7's and report the accuracy for the identification of Lyme meningitis.Results:Of 721 included children with meningitis, 178 had Lyme meningitis (24.7%) and 543 had aseptic meningitis (75.3%). The pooled data from the 4 studies showed the Rule of 7's has a sensitivity of 98% [95% confidence interval (CI): 89%-100%, I-2 = 71%], specificity 40% (95% CI: 30%-50%, I-2 = 75%), and a negative predictive value of 100% (95% CI: 95%-100%, I-2 = 55%).Conclusions:The Rule of 7's accurately identified children with meningitis at low-risk for Lyme meningitis for whom clinicians should consider outpatient management while awaiting Lyme disease test results.