WEDNESDAY, Jan. 3, 2007 (HealthDay News) -- Existing guidelines accurately distinguish between cases of viral and more dangerous bacterial meningitis, reducing the number of unnecessary hospitalizations and antibiotics that are given to children, researchers report.
The tool should also be used by emergency room physicians, concludes the study in the Jan. 3 issue of the Journal of the American Medical Association.
"The previously published and derived 'decision rule' worked well or better than anything else we could come up with," said principal investigator Dr. Lise E. Nigrovic, an attending physician in pediatric emergency medicine at Children's Hospital Boston. "It's the most accurate clinical prediction rule to discriminate between bacterial and viral meningitis."
"This would support some clinicians -- particularly [those] seeing an older child with what looks like viral meningitis -- in saying, 'I don't really need to hospitalize this child now, I can follow him as an outpatient,'" added Dr. Nathan Litman, director of pediatrics and pediatric infectious diseases at Children's Hospital at Montefiore Medical Center in New York City.
Improved diagnosis is incredibly important in treating meningitis, "potentially saving costly hospitalization and potentially avoiding initiating an IV line of antibiotics that would be unnecessary," he said.
Meningitis is a potentially life-threatening inflammation of the membranes (meninges) surrounding the brain and spinal cord. Patients with the condition are usually identified by a higher-than-normal number of white blood cells in the spinal fluid. Most cases of meningitis are caused by viral infections, but about one in 25 are caused by bacterial or fungal infections. Bacterial meningitis, while relatively rare, is much more severe and can lead to disability and even death.
"The conundrum is that you have a very rare but serious disease, bacterial meningitis, and a much more common but less serious viral meningitis," Nigrovic said.
It takes two days for a culture to come back to prove that the meningitis is bacterial or viral. Unfortunately, doctors typically have to decide right away how to treat the patient.
"Often, patients are admitted to the hospital," Nigrovic said. "If a physician was actually able to determine a patient was at low risk for bacterial meningitis before the cultures came back, they might consider treating them as outpatients and avoiding some of the potentially harmful consequences of hospitalization."
The authors of the current study had previously developed the Bacterial Meningitis Score, to help doctors identify patients at very low risk of bacterial meningitis. Individuals were considered at low risk if they lacked five criteria, including certain cerebrospinal fluid measurements and a history of seizures.
But the score was tested only at one medical center. It was also tested before the widespread use of the pneumococcal conjugate vaccine made the bacterial form of the disease much less common in children under age 2.
This time, the score was tested on the records of almost 3,300 children aged 29 days to 19 years, treated at 20 academic medical centers in the United States. The lead institutions were Children's Hospital Boston and the University of California, Davis. Most of the children had been vaccinated for meningitis.
Among this new group of patients, the Bacterial Meningitis Score accurately identified patients with the disease 98.3 percent of the time. The score had a negative predictive value -- meaning it spotted patients without bacterial disease -- of 99.9 percent.
There was one caveat: Children younger than 2 months who have at least one risk factor on the Bacterial Meningitis Score should still be hospitalized and given antibiotics, the authors stated.
"The youngest children are at slightly higher risk, and the rule did not work as well for them, so the rule should be applied to children aged 2 months and older," Nigrovic said.
"They clearly point out exceptions," Litman added. He said that some children who don't have bacterial meningitis would still need to be hospitalized if they had other, life-threatening illnesses.
Ultimately, doctors still need to make their own judgments. "The rule works very accurately at discriminating between the two, but it should be used to assist clinicians in decision-making," Nigrovic said.
More information
To learn more about meningitis, visit the National Meningitis Association.
