Infection Control & Hospital Epidemiology
Table 4. Parameter Estimates and Distributions for E. faecium Infections Used in the Economic Model Variable
Estimate (95% UI)
E. faecium bloodstream infection Rate (resistant þ susceptible) per 10,000 patient days
Mortality, 30-day all cause hospital-onset Probability_VRE Extra LoS_VRE
Mortality_VRE (odds ratio) Treatment (excess cost of antibiotics per infection)
0.20 (0.16,0.25) 0.2615
0.34 (0.27–0.49)
4.89 (0.56–11.52)16 2.57 (2.31–2.90)17
þ$1,622.20 (N/A) Note. UI, uncertainty interval; LoS, length of stay; VRE, vancomycin-resistant E. faecium.
323
Distribution Type (Parameters)
β (0.00003–0.00000248) Fixed value used β (0.343–0.0575) γ (4.89–2.79)
Log-normal (0.943–0.0633) Fixed value used
Table 5. Parameter Estimates and Distributions for S. aureus Infections Used in the Economic Model Variable
Estimate (95% UI)
S. aureus – bloodstream infection Rate (susceptible þ resistant) per 10,000 patient days
Mortality, 30 day all-cause hospital onset Probability of MRSA
Additional LoS for MRSA infection, days Mortality hazard ratio, MRSA
Excess cost of antibiotics per infection
S. aureus respiratory tract infection Rate (susceptible þ resistant) per 10,000 patient days
Probability_of MRSA
Additional LoS for MRSA infection, days Mortality hazard ratio, MRSA
Excess cost of antibiotics per infection
3.91 (3.76–4.18) 0.1518
0.15 (0.13–0.17)
2.54 (−3.19 to 8.27)13 1.26 (0.82–1.94)13
þ$87.40
4.60 (4.38–4.84) 0.13 (0.11–0.15) 0.60 (0–1)14
1.30 (1.0–1.6)14 N/A
Note. UI, uncertainty interval; LoS, length of stay; MRSA, methicillin-resistant S. aureus; N/A, not available.
statistics estimate of the number of days of patient care in all hospitals across Australia (N=18,934,000).21
Synthesis of published studies
Any study published between January 1990 and June 2017 report- ing primary evidence of the health impact of resistant compared to susceptible patients was considered. No language or publication status restrictions were imposed. Studies comparing resistant or susceptible to uninfected groups were included in the original search to ensure that all possible estimates were identified; how- ever, only studies that directly compared resistant to susceptible patients were included in the final economic model. Primary outcomes measures were excess LoS, excess mortality, and treat- ment. Organisms of interest were Enterococcus spp, Escherichia coli, K. pneumoniae, P. aeruginosa, and S. aureus. All study designs were considered, but priority was given to systematic reviews, ran- domized controlled trials, cohort studies, and case-control studies. Studies were identified by searching electronic databases, scanning
reference lists of articles, and consulting with the advisory committee. This search was applied to PubMed, Embase, Cinahl, Cochrane, and DARE (Database of Abstracts of Reviews of Effectiveness). The last search was run in June 2017. In addition, we manually searched the contents pages of the UK Review on Antimicrobial Resistance;
Centres for Disease Control; the Australian Group of Antimicrobial Resistance (AGAR); Enterococcus Surveillance Program; the Australian Staphylococcus aureus Sepsis Outcome Programme; the Enterobacteriaceae Sepsis Outcome Programme and the Australian Commission of Safety and Quality in Healthcare AURA (the Australianreportonantimicrobialuseandresistance inhumanhealth). We developed a data extraction sheet, and one author (T.W.)
extracted information from each included study. Inclusion of each study and extraction of estimates used in the economic model were critiqued by two authors and, where possible, members of the advi- sory committee. All included studies were ranked based on the cri- teria adapted from a published quality-assessment method.4 We prioritized studies that had used a rigorous methodology. The highest-quality studies were those that had appropriately adjusted for time-dependent bias by using multistate modeling.22 Studies that controlled for LoS using other methodologies, such as case-matching or regression analysis or by sensitivity analysis of LoS prior to infection, were categorized as medium quality and were considered the next-best scenario. Studies that did not control or describe adjustment for prior LoS within their method- ology were excluded even if they had adjusted for severity of illness and/or prior antibiotic therapy (ie, low quality). If >1 esti- mate was available and was of equal quality, then the study
Distribution Type (Parameters)
β (0.00039–0.0000107) Fixed value used β (0.152–0.00994) γ (2.54–2.92)
Log-normal (0.231–0.219) Fixed value used
β (0.000460–0.0000117) β (0.128–0.00841) β (0.6–0.255)
Log-normal (−0.916–0.103)
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