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Staph infection numbers moving in wrong direction
Increasing at 7% annually in hospitals
The numbers are in and they aren't good. Data presented recently in Baltimore at the annual meeting of the Society for Healthcare Epidemiology of America document an inexorable increase in staph infections in the nation's hospitals.
"I don't think it is any surprise that the total number of staph infections went up," says Gary Noskin, MD, lead author of the study and a health care epidemiologist at Northwestern Memorial Hospital in Chicago. "But it's hard to know what that means. Does it mean there were more staph infections because we are taking care of sicker and sicker patients? We are able to do surgical procedures [and medical interventions] on patients who are a lot older than [those undergoing the same procedures] 10 to 15 years ago. As the population ages, it may be a reflection of that. It may be a reflection that there are more people at risk. Obviously, dialysis patients, injection drug users, people with diabetes are at increased risk for staph infections."
Noskin and co-researchers analyzed more than 45 million hospital discharge records and found that from 1998 to 2003, the prevalence of S. aureus infection among all patients increased at an annual rate of 7.1%.1 The problem grew even faster among surgical patients, for whom the rate of staph infections rose 7.9% each year for all surgical stays and 9.3% each year for orthopedic patients.
The data were gleaned from the Nationwide Inpatient Sample, billing and discharge data reflecting about 20% of hospitalizations nationally that are submitted to the Agency for Healthcare Research and Quality (AHRQ). However, the data set does not enable researchers to discern whether the infection was caused by drug-susceptible or resistant staph strains, though the CDC projects that MRSA now is causing almost two-thirds of all staph infections.
Indeed, the primary sources to estimate the prevalence of MRSA have been discharge data and surveillance data from Centers for Disease Control and Prevention sentinel hospitals. However, critics charge that the CDC sentinel surveillance is biased somewhat toward large teaching hospitals and MRSA is likely underreported in discharge data. The Association for Professionals in Infection Control and Epidemiology (APIC) is conducting a national prevalence survey that is expected to be presented soon at the 2007 APIC meeting in San Jose, CA. It will be interesting to compare those results to data presented at SHEA, where Noskin and colleagues also offered an assessment of the economic impact of staph infections.
Using the same data set, they found that from 1998 to 2003 the economic burden among all Staph aureus- related inpatient stays increased from $8.7 billion to $14.5 billion, an annual increase of 11.9%.2 "These findings clearly demonstrate the considerable economic implications of Staph aureus infections for hospitals nationwide," Noskin says. "It suggests that there could be large cost savings associated with aggressive efforts to prevent patients from becoming infected with these bacteria. We were able to look at changes compared to patients without staph infections and then look at things like length of stay and comorbidities. The biggest driver of costs in heath care is length of stay in the hospital."