The finding, published in the January 3, 2007, issue of the Journal of the American Medical Association, is based on the review of medical charts from thousands of children diagnosed with meningitis at 20 academic medical centers across the United States from January 2001 to June 2004.

"Using a multi-center network of U.S. hospitals that care for acutely ill children, we showed our algorithm effectively identified children with meningitis who are at very low risk of having bacterial meningitis," says Lise Nigrovic, MD, MPH, of the Division of Emergency Medicine at Children's Hospital Boston and principal investigator of the study. "The finding is important because it gives emergency room physicians nationwide a tool to guide their decision-making when caring for children with suspected meningitis, a serious and potentially life-threatening infection."

Meningitis is an inflammation of the membranes (meninges) surrounding the brain and spinal cord, and is usually initially recognized by a higher number of white blood cells in the spinal fluid than normal. While viral infections cause most meningitis cases, about one in 25 cases are caused by bacterial or fungal infections, which yield the most severe illness. Although the best course of treatment depends on identifying the type of infection, definitive test results can take 24 to 72 hours to process, and children are often admitted to hospitals and started on antibiotics while physicians wait for these results.

"Viral or 'aseptic' meningitis beyond young infancy is usually a mild disease, while meningitis caused by bacteria can cause serious illness and death," says Nathan Kuppermann, MD, MPH, professor and chair of the Emergency Department at UC Davis Medical Center and a senior author on the study. "Even though most patients will turn out to have viral meningitis, pediatric emergency department physicians usually hospitalize any child with meningitis to receive broad-spectrum antibiotics while waiting two to three days for the bacterial culture results." says Kuppermann. "The ability to identify those children who are at very low risk of bacterial meningitis and can be considered for management on an outpatient basis will avoid unnecessary hospitalization and aggressive antibiotic therapy."

Nigrovic developed the algorithm in 2002 with Kuppermann and Richard Malley, MD, of Children's Divisions of Emergency Medicine and Infectious Diseases at Children's Hospital Boston and also a senior author on the study. Known as the Bacterial Meningitis Score, the algorithm uses easily obtained results from routine tests of blood and fluid, including spinal fluid, Gram stain results, neutrophil count and protein concentration, as well as bloodstream neutrophil count. It also takes into account other factors, such as whether the child has had a seizure during the current illness.

"The Bacterial Meningitis Score accurately identified patients at very low risk of bacterial meningitis, misclassifying only 0.1 percent of patients categorized as very low risk," Malley says. "To our knowledge, this is the first bacterial meningitis prediction model to be both externally validated and studied at multiple centers in the era of widespread conjugate pneumococcal immunization."

"Any major change in the epidemiology of a disease has the potential to affect the performance of a prediction rule," Nigrovic says. "We were pleased to find that our prediction tool remains valid now that most infants and toddlers have received the pneumococcal vaccine."

The researchers caution physicians against using the assessment tool for infants younger than 2 months of age, who are at greater risk of bacterial meningitis, and for whom the algorithm was slightly less accurate. They also caution that the tool should not be used to guide decision-making for children who have already received pretreatment with antibiotics before the spinal tap. Nevertheless, widespread implementation of this algorithm could result in a substantial decrease in unnecessary hospitalizations of children who are at very low risk of bacterial meningitis. The researchers plan to further study the best implementation of the rule.

The study was sponsored by the Pediatric Emergency Medicine Collaborative Research Committee of the American Academy of Pediatrics and supported by the Ambulatory Pediatric Association Young Investigator Grant and the National Research Service Award.

Contacts:
Rachel Pugh or Alissa Rooney
617-355-6420
rachel.pugh@childrens.harvard.edu
alissa.rooney@childrens.harvard.edu

Lise Nigrovic, MD, MPH, lead author of the study, is an assistant in the Division of Emergency Medicine at Children's Hospital Boston and an instructor in Pediatrics at Harvard Medical School.

Richard Malley, MD, a senior author on the study, is a physician in the Divisions of Emergency Medicine and Infectious Diseases at Children's Hospital Boston and an assistant professor at Harvard Medical School.

Nathan Kuppermann, MD, MPH, a senior author on the study, is professor, chair, and director of research of the Emergency Department at UC Davis Medical Center.

Children's Hospital Boston is home to the world's largest research enterprise based at a pediatric medical center, where its discoveries have benefited both children and adults since 1869. More than 500 scientists, including eight members of the National Academy of Sciences, 11 members of the Institute of Medicine and 10 members of the Howard Hughes Medical Institute comprise Children's research community. Founded as a 20-bed hospital for children, Children's Hospital Boston today is a 347-bed comprehensive center for pediatric and adolescent health care grounded in the values of excellence in patient care and sensitivity to the complex needs and diversity of children and families. Children's also is the primary pediatric teaching affiliate of Harvard Medical School. For more information about the hospital and its research visit: www.childrenshospital.org/newsroom.

UC Davis Health System is a premier academic medical center whose mission is to discover and share knowledge to advance health and to provide the highest quality of care to patients. Among the nation's leading research institutions, UC Davis focuses on advancing medical knowledge and bringing new treatments to address the scientific and health challenges facing the world. The health system includes UC Davis School of Medicine, the 577-bed acute-care hospital and clinical services of UC Davis Medical Center, and the 800-member physician group known as UC Davis Medical Group.