Predictive model for Lyme meningitis: a reply.
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Publications and source records attributed to Robert A Avery.
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BACKGROUND: Differentiating Lyme meningitis (LM) from other forms of aseptic meningitis (AM) in children is a common diagnostic dilemma in Lyme disease-endemic regions. Prior studies have compared clinical characteristics of patients with LM versus patients with documented enteroviral infections. No large studies have compared patients with LM to all patients presenting with AM and attempted to define a clinical prediction model. OBJECTIVE: To create a statistical model to predict LM versus AM in children based on history, physical, and laboratory findings during the initial presentation of meningitis. METHODS: Children older than 2 years presenting to the Alfred I. duPont Hospital for Children between October 1999 and September 2004 were identified if both Lyme serology and cerebrospinal fluid (CSF) were collected during the same hospital encounter. Patients were considered to have Lyme disease only if they met Centers for Disease Control and Prevention criteria (documented erythema migrans and/or positive Lyme serology). Patients were eligible for study inclusion if they had documented meningitis (CSF white blood cell count: >8 per mm3). Retrospective chart review abstracted duration of headache and cranial neuritis (papilledema or cranial nerve palsy) on physical examination and percent CSF mononuclear cells. Using logistic-regression analysis, the type of meningitis (LM versus AM) was simultaneously regressed on these 3 variables. The Hosmer-Lemeshow test was performed and the area under the receiver operating characteristic curve was calculated. RESULTS: A total of 175 children with meningitis were included in the final statistical model. Logistic-regression analysis included 27 patients with LM and 148 patients classified as having AM. Duration of headache, cranial neuritis, and percent CSF mononuclear cells independently predicted LM. The Hosmer-Lemeshow test revealed a good fit for the model, and the Nagelkerke R2 effect size demonstrated good predictive efficacy. Odds ratios based on the logistic-regression results were calculated for these variables. The final model was transformed into a clinical prediction model that allows practitioners to calculate the probability of a child having LM. CONCLUSIONS: Longer duration of headache, presence of cranial neuritis, and predominance of CSF mononuclear cells are predictive of LM in children presenting with meningitis in a Lyme disease-endemic region. The clinical prediction model can help guide the clinician about the need for parenteral antibiotics while awaiting serology results.
BACKGROUND: Cerebrospinal fluid (CSF) laboratory tests are frequently collected to help differentiate Lyme meningitis from other causes of aseptic meningitis. Previous studies using Lyme CSF polymerase chain reaction (PCR) have yielded varied results (sensitivity between 10 and 90%). No studies have specifically examined the diagnostic utility of Lyme CSF-PCR in North American children with Lyme meningitis. METHODS: Retrospective chart review of children presenting to a children's hospital in a Lyme-endemic region between October 1999 and September 2004. Patients were included if they had both Lyme serology and Lyme CSF-PCR performed during the same hospital encounter and had documented meningitis. Patients were considered to have Lyme meningitis if they had meningitis and met CDC criteria for Lyme disease. The Lyme CSF-PCR assay amplified a Borrelia burgdorferi DNA flagellin gene sequence. RESULTS: Of 108 patients with meningitis who qualified for the study, 20 patients met criteria for Lyme meningitis and 88 were classified as aseptic meningitis. Positive Lyme CSF-PCR was found in 1 patient (1 of 20, 5%) with Lyme meningitis and one patient classified as aseptic meningitis (1 of 88, 1%). Lyme CSF-PCR had a sensitivity of 5% and a specificity of 99%. The only Lyme meningitis patient with positive Lyme CSF-PCR had the highest CSF white blood cell count and CSF protein values compared with the other Lyme meningitis patients. CONCLUSIONS: This is the first study to evaluate Lyme CSF-PCR exclusively in North American children. This commercially available laboratory test is not generally helpful for identifying Lyme meningitis because of its low sensitivity.