Should CDC expand NNIS system?

Burke JP. Infection control — a problem for patient safety. New Engl J Med 2003; 348:651-656.

In an era of patient safety, the author urged national expansion of the Centers for Disease Control and Prevention’s (CDC) National Nosocomial Infection Surveillance (NNIS) System. Despite its flaws and limited scope, the NNIS system may be a model for patient safety data collection.

"The importance of the patient-safety movement in energizing infection control is already manifest," he stated. "Many infection control units have broadened their activities in monitoring the use of antibiotics and in preventing adverse drug events due to antibiotics."

Perhaps the most important outcome of the NNIS System is the infrastructure of trained infection control professionals that it has nurtured and the cadre of CDC-trained infectious disease physicians who have migrated to university and community hospitals during the past 30 years.

"These human resources are now endangered because of the economic forces shaping health care and the downsizing of many, if not most, infection control units in hospitals," he wrote.

The voluntary nature of NNIS may be an important factor in its success, but participation also helps hospitals meet regulatory requirements. In addition, the support of CDC epidemiologists is a vital asset. The voluntary, confidential, hospital-based reporting system has been influential in guiding infection control efforts in hospitals across the United States and around the world. It is the only national source of systematically gathered data on hospital infections.

Monthly reports of nosocomial infections allow benchmarks for infection rates to be established through the use of standardized case definitions and data collection methods and computerized data entry and analysis.

"More than a decade ago, the Institute of Medi-cine called for further development of the NNIS System and its expansion to include more US hospitals; indeed, the system has grown rapidly, from 120 hospitals in 1991 to more than 300 in 2001," he stated. "Broader participation among all U.S. hospitals is even more urgent today."

However, each hospital participating in the NNIS System provides data on only one or two high-risk components of surveillance, such as intensive care or selected surgical procedures. In addition, case ascertainment is time-consuming and costly for hospitals, and the definitions for infections are complex and difficult to apply.   

Therefore, the NNIS System is a model for focused surveillance but not for overall infection control. This system has not yet addressed many important safety issues, such as clinical errors of omission leading to failures to diagnose infection or delays in the diagnosis of infection.

Furthermore, the definitions used during surveillance (for example, the definitions for ventilator-associated pneumonia and for infections developing after hospital discharge) are a work in progress, the author concluded.