Quantifying cost-effectiveness of controlling nosocomial spread of antibiotic-resistant bacteria: the case of MRSA.
BACKGROUND
The costs and benefits of controlling nosocomial spread of antibiotic-resistant bacteria are unknown.


METHODS
We developed a mathematical algorithm to determine cost-effectiveness of infection control programs and explored the dynamical interactions between different epidemiological variables and cost-effectiveness. The algorithm includes occurrence of nosocomial infections, attributable mortality, costs and efficacy of infection control and how antibiotic-resistant bacteria affect total number of infections: do infections with antibiotic-resistant bacteria replace infections caused by susceptible bacteria (replacement scenario) or occur in addition to them (addition scenario). Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia was used for illustration using observational data on S. aureus bacteremia (SAB) in our hospital (n = 189 between 2001-2004, all being methicillin-susceptible S. aureus [MSSA]).


RESULTS
In the replacement scenario, the costs per life year gained range from 45,912 euros to 6590 euros for attributable mortality rates ranging from 10% to 50%. Using 20,000 euros per life year gained as a threshold, completely preventing MRSA would be cost-effective in the replacement scenario if attributable mortality of MRSA is > or = 21%. In the addition scenario, infection control would be cost saving along the entire range of estimates for attributable mortality.


CONCLUSIONS
Cost-effectiveness of controlling antibiotic-resistant bacteria is highly sensitive to the interaction between infections caused by resistant and susceptible bacteria (addition or replacement) and attributable mortality. In our setting, controlling MRSA would be cost saving for the addition scenario but would not be cost-effective in the replacement scenario if attributable mortality would be < 21%.
Wassenberg
Marjan W M
MW
Department of Internal Medicine and Infectious Diseases, University Medical Center, Utrecht, The Netherlands. M.W.M.Wassenberg@umcutrecht.nl
de Wit
G Ardine
GA
van Hout
Ben A
BA
Bonten
Marc J M
MJ
D000465:Algorithms; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D003140:Communicable Disease Control / Q000191:economics*; D003362:Cost-Benefit Analysis; D024901:Drug Resistance, Multiple, Bacterial; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000472:pathogenicity*; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000635:transmission
D000900:Anti-Bacterial Agents