A new review of inpatient data from U.S. hospitals shows that the number of infections caused by a common bacterium increased by over 7 percent each year from 1998 to 2003.
The attendant economic burden to hospitals increased by nearly 12 percent annually. The research is published in the November 1 issue of Clinical Infectious Diseases, now available online.
Staphylococcus aureus (also known as staph) is a significant cause of a wide range of infectious diseases in humans, ranging from minor skin infections to life-threatening diseases such as pneumonia and meningitis. In 1998, US hospitals reported a little more than a quarter-million staph infections and slightly over 7 percent of those patients died. By the final year of this study, 2003, hospitals reported nearly 390,000 infections, representing 1 percent of that year's inpatient stays.
The authors suggest one possible reason for the increase in infections is the documented increase of a particularly dangerous type of antibiotic-resistant staph infection known as MRSA (methicillin-resistant Staphylococcus aureus). A more benign possibility is that doctors and hospitals have improved their infection detection and reporting practices.
The good news is that the staph-related in-hospital mortality rate dropped by almost 5 percent each year. The decrease in the in-hospital mortality risk may be due to the introduction of more stringent infection control programs or due to appropriate early treatment of MRSA infections with an effective antibiotic, the authors write.
Hospital expenditures associated with staph infections are substantial, increasing from $8.7 billion in 1998 to $14.5 billion in 2003. This economic burden incorporates such factors as extended length of hospitalization and additional surgery, medications, lab tests, and radiologic studies. Lead author Gary Noskin, MD, of Northwestern Memorial Hospital in Chicago, hypothesized that the reason the economic burden increased at a faster pace than the number of infections is because hospital costs are increasing more quickly.
The authors used data from the Agency for Healthcare Research and Quality's Nationwide Inpatient Sample database, which contains data from approximately 7 million hospital stays annually.
Unfortunately, the authors were not able to determine the contribution of MRSA infections to costs or outcomes because hospitals generally use the same codes for MRSA and regular staph infections. “We do suggest that coding standards should be changed to more accurately reflect the difference between these two bacteria so we can better understand the impact of MRSA,” said Dr. Noskin.