Diagnostic performance of the bacterial meningitis score in the emergency department patients: a multicenter retrospective study.

Abstract

Background and importance: The bacterial meningitis score (BMS) is a validated clinical prediction rule for identifying children at very low risk of bacterial meningitis based on five criteria. Whether BMS is safe to rule out bacterial meningitis in adults is unknown.

Objectives: The primary objective was to evaluate the performance of the BMS to identify adults at low risk of bacterial meningitis.

Design: This 4-year-period multicentric retrospective diagnostic study was conducted in 15 adult emergency departments (EDs) in France. Immunocompetent patients with meningitis, defined as cerebrospinal fluid (CSF) pleocytosis (CSF white blood cells ≥ 5/µl), were included among patients with an ED report including a lumbar puncture code procedure or a diagnosis of meningitis according to the International Classification of Diseases, 10 th Revision classification. The reference standard for bacterial meningitis was a positive bacterial CSF culture.

Outcome measures and analysis: The main outcome was the negative predictive value (NPV) of the BMS for the diagnosis of bacterial meningitis. The secondary outcome was the proportion of meningeal-dose antibiotic treatments that could have been avoided for patients with BMS = 0. The performances of the BMS when combined with intrathecal lactate, blood procalcitonin (PCT), and C-reactive protein (CRP) were also assessed.

Main results: Among the 995 patients identified, 531 (13.3%) were eligible, and 456 patients (85.9%) with meningitis and a usable BMS were included. Seventy-three (16.0%) presented bacterial meningitis, with a majority of Streptococcus pneumoniae (n  = 35, 47.9%) and Neisseria meningitidis (n  = 10, 13.7%), and 383 (84.0%) had aseptic meningitis. There was one patient with bacterial meningitis and a BMS score of 0 [NPV: 99.5%, 95% confidence interval (CI): 97.4-100]. The proportion of avoidable antibiotics was 64.1% (95% CI: 57.3-70.3). The NPV was 100% (95% CI: 94.6-100), 97.9% (95% CI: 92.5-99.7), and 98.9% (95% CI: 96.1-99.9) for combined BMS with intrathecal lactate greater than or equal to 2 mmol/l, blood PCT greater than or equal to 0.29 µg/l, and blood CRP greater than or equal to 24 mg/l, respectively.

Conclusion: The BMS score presents a very high NPV, with the potential of safely ruling out bacterial meningitis among ED patients with positive CSF results.