Staphylococcus aureus infections (S. aureus) create an enormous burdento hospitals by significantly increasing costs, length of patient staysand mortality rates, a Northwestern Memorial Hospital researcher foundin the most comprehensive study to date, published today's Archives ofInternal Medicine. The study, led by Gary Noskin, MD, an infectiousdiseases specialist and medical director of healthcare epidemiology andquality at Northwestern Memorial, examined two years of data fromhundreds of hospitals.
"S. aureus infections represent a considerable burden to U.S.hospitals, particularly among high-risk patient populations," said Dr.Noskin. "The potential benefits to hospitals in terms of reduced use ofresources and costs, as well as improved outcomes from preventing S.aureus infections, are significant."
"There are currently a number of things being done to reducethe number of hospital-acquired S. aureus infections, including use ofantibiotics to prevent surgical site infections, consistenthand-washing and maximum barrier protections when putting in centrallines," adds Dr. Noskin. "There are also strategies to reduce S. aureusinfections that are brought into the hospital such as performing anasal swab to screen for S. aureus then attempting to eliminate it.Another important intervention is to make sure patients with certaininfections are placed in isolation."
S. aureus infection was listed as a discharge diagnosis innearly 1 percent of all hospital stays, or an average of 292,045 staysin a year, the study found. And S. aureus infection stays had, onaverage, 3 times the length of stay (14.3 vs. 4.5 days), three timesthe total charges ($48,824 vs. $14,141), and five times the risk ofin-hospital death (11.2 percent vs. 2.3 percent) than stays withoutthis infection. Even when controlling for patient differences in age,gender, race and comorbidities, the differences were significant: 9.1days in excess length of stay, $32,856 in excess charges and 4 percentin-hospital mortality.
Applying these per stay estimates to the total number of S.aureus stays in the United States in a given year results in anestimated 2.7 million days in excess length of stay, $9.5 billion inexcess charges, and close to 12,000 inpatient deaths per year. Thedifferences remained significant when also comparing hospitalizationswith S. aureus infections with other types of infections.
The study did not distinguish between infections that occurredbefore admission to the hospital or during a hospital stay. Also, theinability to measure "out of hospital" mortality, or mortalitysubsequent to the hospital stay, likely underestimates the impact of S.aureus infections on mortality.
S. aureus is a bacterium, frequently living on the skin or in the noseof a healthy person that can cause illnesses ranging from minor skininfections and abscesses, to life-threatening diseases. Long recognizedas a frequent cause of healthcare-associated infections in acute carehospitals, it is often responsible for hospital-acquired pneumonia andsurgical site infections, and is the second most common cause ofbloodstream infections. An increasing percentage of S. aureusinfections are caused by antibiotic resistant strains of the organism.
3M Healthcare was a study sponsor and financial support alsocame from a grant from the U.S. Public Health Service. According toEdwin Hedblom, health economic business manager from 3M Health Care,"no prior study has estimated the impact of S. aureus infections tothis degree, in terms of clinical and financial outcomes that includelength of stay (LOS), total charges, and in-hospital mortality, fromnationally representative data."
Patient discharge data from 994 hospitals in 28 states in 2000and 986 hospitals in 33 states in 2001 -- representing approximately 14millions inpatient stays -- was analyzed to determine the associationof S. aureus infections with length of stay, total charges andin-hospital mortality.
Other findings include:
- Patients undergoing an orthopedic, cardiovascular, and neurosurgical procedure that have S. aureus infection spent 16.6 additional days in the hospital and at a cost of $68,944 as compared to patients without S. aureus infections.
- Patients undergoing an orthopedic, cardiovascular or neurosurgical procedure with S. aureus infections had a nearly five-fold risk of in-hospital death compared to patients without this infection. The differential in absolute risk of mortality was greatest for cardiovascular procedures.
- Among the hospitalizations analyzed, S. aureus infections were most likely to occur in neurosurgery stays (1.4 percent) and least likely to occur in orthopedic surgery stays (0.3 percent).
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