Risk factors and costs associated with methicillin-resistant Staphylococcus aureus bloodstream infections.
OBJECTIVE
To compare the cost of hospitalization of patients with methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI) versus patients with methicillin-sensitive S. aureus (MSSA) BSI, controlling for severity of underlying illness; and to identify risk factors associated with MRSA BSI.


METHODS
Retrospective case-control study based on medical chart review.


METHODS
A 640-bed, tertiary-care hospital in Seattle, Washington.


METHODS
All patients admitted to the hospital between January 1, 1997, and December 31, 1999, with S. aureus BSI confirmed by culture.


RESULTS
Twenty patients with MRSA BSI were compared with 40 patients with MSSA BSI. Univariate analysis identified 5 risk factors associated with MRSA BSI. Recent hospital admission (P = .006) and assisted living (P = .004) remained significant in a multivariate model. Costs were significantly higher per patient-day of hospitalization for MRSA BSI than for MSSA BSI (dollar 5,878 vs dollar 2,073; P = .003). When patients were stratified according to severity of illness as measured by the case mix index, a difference of dollar 5,302 per patient-day was found between the two groups for all patients with a case mix index greater than 2 (P < .001).


CONCLUSIONS
These observations suggest that MRSA BSI significantly increases hospitalization costs compared with MSSA BSI, even when controlling for the severity of the patient's underlying illness. As MRSA BSI was also found to be significantly associated with a group of patients who have repeated hospitalizations, such infections contribute substantially to the increasing cost of medical care.
McHugh
Carolyn Guertin
CG
Division of Infectious Diseases, School of Public Health, University of California, Berkeley, California 94720, USA.
Riley
Lee W
LW
D000368:Aged; D016022:Case-Control Studies; D017281:Cost of Illness; D005260:Female; D006801:Humans; D008297:Male; D016106:Methicillin Resistance; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000097:blood / Q000191:economics* / Q000453:epidemiology* / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification*; D014861:Washington / Q000453:epidemiology