Cost-Effective Analysis of Empiric Antibiotic Therapy For Suspected Enterococcal Bacteremia

1. Cost-Effective Analysis of Empiric Antibiotic Therapy For Suspected Enterococcal Bacteremia Tom Hsiung, B.S.Pharm, ID 15221010857 SOP, China Pharmaceutical University Nanjing, Jiangsu, China

2. Background • Bloodstream infections • ~ 1/3 of hospital-acquired infection • Significant morbidity (most often, LKC-CNS) • Significant mortality • Epidemiology of Enterococcus • 10% of all bloodstream infections

3. The Overall Process • Step 1 Identify the specific decision • Step 2 Specify Alternatives • Step 3 Draw the Decision Analysis Structure • Step 4 Specify Possible Costs, Outcomes, and Probabilities • Final Step Perform Calculations

4. Steps • Step 1 Identify the specific decision • Objective • Perspective • Time interval

5. Step 1 Identify the Specific Decision • Objective • Gram stain cocci (+) [Blood] • Cost-effectiveness • Perspective – Patient, Provider, Payer, and Societal • Cost • Direct cost (drugs, supplies, lab test, provider’s time, hospitalization) • Outcome – Clinical and Humanistic • Time Interval – 30 days after hospitalization

6. Steps • Step 2 Specify Alternatives • Most effective treatments • Innovative approach vs standard approach

7. Step 2 Specify Alternatives • Antibiotic Approaches • Beta-lactam agent (standard) • Vancomycin (standard) • Antibiotics against vancomycin-resistant enterococci

8. Steps • Step 3 Draw the Decision Analysis Structure • Choice node • Chance node • Terminal node

9. Steps • Step 4 Specify Possible Costs, Outcomes, and Probabilities • Probability of occurrence • Consequences of the occurrence

10. Step 4 Specify Possible Costs, Outcomes, and Probabilities • Costs • Ampicillin 2000 mg Q6h $27 • Vancomycin 1000 mg twice/day $8 • Daptomycin 420 mg/day $254 • Linezolid 600 mg IV twice/day $241 • Days until species identified 2 days • Days until susceptibilities return 4 days • Vancomycin-susceptible • Vancomycin-resistant enterococcus • Increased length of stay if not susceptible 0 days

11. Step 4 Specify Possible Costs, Outcomes, and Probabilities • Probabilities, Outcomes • Gram positive cocci in chains identified as enterococcal50% • Prevalence of E. faecalis35% • Ampicillin susceptible 100% • Vancomycin susceptible 96% • Daptomycin susceptible 100% • 30-day mortality when susceptible to empiric 10% • 30-day mortality when non-susceptible empiric 13%

12. Step 4 Specify Possible Costs, Outcomes, and Probabilities • Probabilities, Outcomes • Prevalence of E. faecium51% • Ampicillin susceptible 5.4% • Vancomycin susceptible 28.3% • Daptomycin susceptible 99.7% • 30-day mortality when susceptible to empiric 26% • 30-day mortality when non-susceptible empiric 45%

13. Step 4 Specify Possible Costs, Outcomes, and Probabilities • Probabilities, Outcomes • Prevalence of other enterococcal species 14% • Ampicillin susceptible 86% • Vancomycin susceptible 86% • Daptomycin susceptible 100% • 30-day mortality when susceptible to empiric 10% • 30-day mortality when non-susceptible empiric 13%

14. Steps • Final Step Perform Calculations • Costs • Consequences

15. Final Step Perform Calculations • Costs of decision 1 • Arm 1 = (P1*P2*…Pn)*[∑(total cost of Arm1)] • Arm 2 • Arm n • Total costs of decision 1 = Arm 1+Arm 2+…+Arm n • Costs of decision 2 • Costs of decision n

16. Final Step Perform Calculations • Outcomeof decision 1 • Arm 1 = (P1*P2*…Pn)*(Outcomeof Arm1) • Arm 2 • Arm n • Total outcomeof decision 1 = Arm 1+Arm 2+…+Arm n • Outcomeof decision 2 • Outcome of decision n

17. Acknowledgement Thank You