Cost-Effectiveness of Preoperative Screening and Eradication of Staphylococcus aureus Carriage

BACKGROUND: Preoperative screening for nasal S. aureus carriage, followed by eradication treatment of identified carriers with nasal mupirocine ointment and chlorhexidine soap was highly effective in preventing deep-seated S. aureus infections. It is unknown how cost-effectiveness of this intervention is affected by suboptimal S. aureus screening. We determined cost-effectiveness of different preoperative S. aureus screening regimes. METHODS: We compared different screening scenarios (ranging from treating all patients without screening to treating only identified S. aureus carriers) to the base case scenario without any screening and treatment. Screening and treatment costs as well as costs and mortality due to deep-seated S. aureus infection were derived from hospital databases and prospectively collected data, respectively. RESULTS: As compared to the base case scenario, all scenarios are associated with improved health care outcomes at reduced costs. Treating all patients without screening is most cost-beneficial, saving €7339 per life year gained, as compared to €3330 when only identified carriers are treated. In sensitivity analysis, outcomes are susceptible to the sensitivity of the screening test and the efficacy of treatment. Reductions in these parameters would reduce the cost-effectiveness of scenarios in which treatment is based on screening. When only identified S. aureus carriers are treated costs of screening should be less than €6.23 to become the dominant strategy. CONCLUSIONS: Preoperative screening and eradication of S. aureus carriage to prevent deep-seated S. aureus infections saves both life years and medical costs at the same time, although treating all patients without screening is the dominant strategy, resulting in most health gains and largest savings

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%

Effect of suboptimal adherence to preoperative <i>S. aureus</i> screening and test sensitivity on cost per life year gained (discounted) per 1000 patients for different screening scenarios.

<p>Scenario 1 is treatment of <i>S. aureus</i> carriers identified by screening; scenario 2 is treatment of <i>S. aureus</i> carriers identified by screening <i>plus</i> treatment of all patients that were not screened. In scenario 1 the life years gained and costs increase, or decrease, at a constant rate resulting in an invariable cost per life years gained. Note the negative costs on the y-axis representing cost-savings.</p

Life expectancy of patients with deep-seated postoperative <i>S. aureus</i> infections.

a<p>17 patients (46%) are included in estimate of the cost of a postoperative surgical site infection.</p

The nosocomial transmission rate of animal-associated ST398 meticillin-resistant Staphylococcus aureus

The global epidemiology of meticillin-resistant Staphylococcus aureus (MRSA) is characterized by different clonal lineages with different epidemiological behaviour. There are pandemic hospital clones (hospital-associated (HA-)MRSA), clones mainly causing community-acquired infections (community-associated (CA-)MRSA, mainly USA300) and an animal-associated clone (ST398) emerging in European and American livestock with subsequent spread to humans. Nosocomial transmission capacities (RA) of these different MRSA types have never been quantified. Using two large datasets from MRSA outbreaks in Dutch hospitals (dataset 1, the UMC Utrecht for 144 months; dataset 2, 51 hospitals for six months) and a recently developed mathematical model, we determined the genotype-specific RA for ST398 and non-ST398 isolates (categorized as HA-MRSA), using observational data, the detection rate of MRSA carriage and the discharge rate from hospital as the input. After detection of 42 MRSA index cases in dataset 1 (all non-ST398 MRSA) 5076 people were screened, yielding 30 secondary cases. In dataset 2, 75 index cases (51 non-ST398 MRSA and 24 ST398) resulted in 7892 screened individuals and 56 and three secondary cases for non-ST398 MRSA and ST398, respectively. The ratio between discharge and the detection rate was 2.7. RA values (95% confidence interval (CI)) were 0.68 (0.47–0.95) for non-ST398 MRSA in dataset 1, 0.93 (0.71–1.21) for non-ST398 MRSA in dataset 2 and 0.16 (0.04–0.40) for ST398. The RA ratio between non-ST398 MRSA and ST398 was 5.90 (95% CI 2.24–23.81). ST398 is 5.9 times less transmissible than non-ST398 MRSA in Dutch hospitals, which may allow less stringent transmission-control measures for ST398 MRSA

Direct health care costs of patients readmitted because of a postoperative surgical site infection between 2001 and 2010.

a<p>Missing information on 8 patients.</p>b<p>Missing information on 1 patient.</p>c<p>Missing information on 3 patients.</p>d<p>Costs of antibiotic treatment were not included.</p

Effect of suboptimal adherence to preoperative <i>S. aureus</i> screening on total costs and life years gained (discounted) per 1000 patients for scenario 1 (only identified <i>S. aureus</i> carriers are treated) and scenario 2 (identified <i>S. aureus</i> carriers and non-screened patients are treated).

<p>Note the negative costs on the y-axis representing cost-savings.</p

Cost-analysis of different strategies per 1000 patients undergoing prosthetic joint or cardiopulmonary surgery.

<p>Cost-analysis of different strategies per 1000 patients undergoing prosthetic joint or cardiopulmonary surgery.</p

Effect of suboptimal adherence to preoperative <i>S. aureus</i> screening and treatment effectiveness on cost per life year gained (discounted) per 1000 patients for different screening scenarios.

<p>Scenario 1 is treatment of <i>S. aureus</i> carriers identified by screening; scenario 2 is treatment of <i>S. aureus</i> carriers identified by screening <i>plus</i> treatment of all patients that were not screened. In scenario 1 the life years gained and costs increase, or decrease, at a constant rate resulting in an invariable cost per life years gained. Note the negative costs on the y-axis representing cost-savings.</p