There was large multicenter study confirmed the Bacterial Meningitis Score prediction rule in the era of conjugate 
pneumococcal vaccine as an accurate decision support tool. The Bacterial Meningitis Score may be helpful to guide clinical decision making for the management of children presenting to emergency departments with CSF pleocytosis, according to an article in medio January 2007 one of JAMA Pediatrics Journals.
The Bacterial Meningitis Score, in which previously known as a clinical prediction rule, classifies patients into bacterial meningitis if they lack all of these criterias: positive CSF Gram stain, CSF absolute neutrophil count (ANC) of at least 1000 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.
But according to this article, clinical prediction rules are often less accurate when tested in a new clinical setting. For it because the assessment of either the predictor or outcome variables may not be reproducible with new patients and physicians or/and the epidemiology of the disease or associated diagnostic testing studied may change over time and thus potentially affect the performance of any prediction rule. Therefore, the observed relationships between predictors and outcome may depend on unique characteristics of the derivation population and may differ if tested in a new patient population.Thus, a model should be validated externally using a different patient population and clinical setting before implementing a clinical prediction rule.
Lise E. Nigrovic, MD, MPH, Department of Medicine, Children’s Hospital Boston, and colleagues from 20 academic medical centers, as part of the Pediatric Emergency Medicine Collaborative Research Committee of the American Academy of Pediatrics, performed a validation study to validate the Bacterial Meningitis Score in the era of widespread conjugate pneumococcal vaccination on a large population of children evaluated in emergency departments across the United States. In other words, they want to measure the sensitivity and negative predictive value of the Bacterial Meningitis Score.
The researchers presented all children aged 29 days to 19 years who 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. They described their methods which consist of work description of Multicenter Collaborative Research Network, Patient Identification, Inclusion and Exclusion Criteria, Case Definition, Data Collection, and both Bacterial Meningitis Score Validation and Refinement.
And the result was,
Using the Bacterial Meningitis Score prediction rule to assist with clinical decision making could substantially reduce unnecessary hospital admissions for children with CSF pleocytosis at very low risk of bacterial meningitis.
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