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Monday, Oct. 8: Modeling in CE analysis

Monday, Oct. 8: Modeling in CE analysis. by  Donald S. Shepard, Ph.D. Schneider Institute for Health Policy Heller School, MS 035 Brandeis University Waltham, MA 02454-9110 USA Tel: 781-736-3975 • Fax: 781-736-3965 Web: http://www.sihp.brandeis.edu/shepard E-mail: Shepard@Brandeis.edu.

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Monday, Oct. 8: Modeling in CE analysis

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  1. Monday, Oct. 8:Modeling in CE analysis by  Donald S. Shepard, Ph.D. Schneider Institute for Health Policy Heller School, MS 035 Brandeis University Waltham, MA 02454-9110 USA Tel: 781-736-3975 • Fax: 781-736-3965 Web: http://www.sihp.brandeis.edu/shepard E-mail: Shepard@Brandeis.edu 1

  2. Practical information • Teaching assistant: Jsuaya@Brandeis.edu • Administrative assistant: Linda Purrini, Next to library in Heller 781-736-3930 Purrini@Brandeis.edu • Cost of packet: $6.00 2

  3. Cost-effectiveness of alternative peri-natal AZT regimens 3

  4. Cost-Effectiveness of Sildenafil, 1 Abstract Background: Coverage of sildenafil by health insurance plans is a contentious issue. Objective: To evaluate the cost-effectiveness of sildenafil treatment for erectile dysfunction. Design: A Markov decision model to estimate the incremental cost-effectiveness of sildenafil compared with no drug therapy. 4

  5. Cost-Effectiveness of Sildenafil, 2 Data Sources: Values for the efficacy and safety of sildenafil and quality-of-life utilities were obtained from the published medical literature. Base-case values were chosen to bias against sildenafil use. Target Population: Men 60 years of age with erectile dysfunction. 5

  6. Cost-Effectiveness of Sildenafil, 3 Time Horizon: Lifetime. Perspective: Societal and third-party payer. Intervention: Sildenafil or no treatment in identical hypothetical cohorts. Outcome Measures: Cost per quality-adjusted life-year (QALY) gained. 6

  7. Markov model for erectile dysfunction 7

  8. 8

  9. 9

  10. Cost-Effectiveness of Sildenafil, 4 Results of Base-Case Analysis: The cost per QALY gained for sildenafil treatment compared with no therapy was $11 290 from the societal perspective and $11 230 from the third-party payer perspective. 10

  11. Sildenafil, sensitivity analysis 11

  12. Cost-Effectiveness of Sildenafil, 5 Results of Sensitivity Analysis: From the societal perspective, the cost per QALY gained associated with sildenafil was less than $50,000 if treatment-related morbidity was less than 0.8% per year, mortality was less than 0.55% per year, treatment was successful in more than 40.2% of patients, or sildenafil cost less than $244 per month. The results were sensitive to variation of erectile dysfunction utilities, but cost per QALY gained was less than $50,000 if successful treatment increased utility values by 0.05 or more on a scale of 0 (death) to 1 (perfect health). 12

  13. Cost-Effectiveness of Sildenafil, 6 Conclusions: In an analysis biased against use of sildenafil, the cost-effectiveness of sildenafil treatment compared favorably with that of accepted therapies for other medical conditions. 13

  14. Cost-Effectiveness of Dengue Control Source: Shepard, D.S. and Halstead, S.B. Dengue (with notes on yellow fever and Japanese encephalitis). In: Disease Control Priorities for Developing Countries, Jamison, D.T., Mosley, W.H., and Measham, A.R., eds. Bobadilla J.L., New York: Oxford University Press for the World Bank, pp. 303-320, 1993. 14

  15. Model for dengue case management Dengue infections with no interventions (CASES) SHOCK.R Dengue Hemorrhagic Fever Dengue Shock Syndrome DHF/DSS No serious illness FATAL Would die without improved case management SALVAGE Die despite improved case management Recover 15

  16. Model for dengue vaccine Healthy, no infection (STAND.POP) COVERAGE Receive vaccination No vaccination VACC.EF Dengue infection No dengue infection Dengue infection No dengue infection CASES Dengue infection (CASES) 16

  17. Dengue model variables: Morbidity and mortality STAND.POP: The number of persons in the standard population (an arbitrary size) to which the model is applied. Here STAND.POP is one million persons of all ages. CASES: Number of dengue infections without vaccination or vector control in the hypothetical birth cohort (all births within the standard population in one year). SHOCK.R (Shock rate): Proportion of dengue infections that progress to dengue shock syndrome. FATAL: Case-fatality rate of DDS 1960-65. CLINICAL: Proportion of dengue infections which are clinically apparent. DUR: Average duration of clinical illness, expressed in disability-adjusted life years. COHORT: Number of persons in one year's birth cohort in the standard population. 17

  18. Dengue model variables: Effectiveness YEAR.D: Discounted remaining life expectancy of a person at the average age of death of a fatal dengue case. SALVAGE: Proportional reduction in case fatality rate of DHF/DSS after improved case management. SHORTEN: Proportional reduction in duration of illness among hospitalized cases after improved case management. VACC.EF (vaccine efficacy): Proportional reduction in number of cases. COVERAGE: Proportion of birth cohort vaccinated. VCTRC.EF: (vector chemical efficacy): Proportional reduction in number of cases from chemical vector control. VCTRE.EF: (vector environmental efficacy): Proportional reduction in number of cases from environmental vector control. 18

  19. Dengue model:Model for single interventions At the baseline (policy BASE): D.BASELINE = CASES  SHOCK.R  FATAL. With case management improved (policy C): DEATHS = CASES  SHOCK.R  FATAL • (1 -SALVAGE). With immunization or vaccination (policy I): DEATHS = CASES (1 - VACC.EF  COVERAGE)  SHOCK.R  FATAL. For each strategy, the number of deaths averted is D.AVERTED = D.BASELINE - DEATHS. 19

  20. Dengue model:Two-way combinations of interventions With vaccination and case management (policy IC): DEATHS = CASES • ( 1 - VACC.EF • COVERAGE) • SHOCK.R • (1 - SALVAGE) •FATAL. 20

  21. Table 2. Efficacy and Costs of Inter-ventions for Dengue (per 1 million pop.) 21

  22. Table 3. Incremental Cost-Effectiveness of Interventions for Dengue Control 22

  23. Legend to Dengue CE graphs • Efficient policies • Inefficient policies  Note: BASE = Baseline; Efficient policies : C = Improved case management, VC = Vector chemically controlled and case management, IC = Vaccination and case management; IVC = Vaccination, case management, and vector chemically controlled, EC = Environmental vector control and case management, ICE = Vaccination, case management, and environmental vector control; Inefficient policies: V = Vector chemically controlled, I = Immunization, IV = Immunization and vector chemically controlled, E = Environmental vector control, IE = Immunization and environmental control. 23

  24. Figure 4. DALYs saved with vaccine in developed health system 24

  25. Fig 5. Deaths averted with vaccine in developed health system 25

  26. Final Assignment of CE module, 1 Purpose: See how cost-effectiveness analysis can be applied to a subject of interest to you. Background: Select and cite an article or report of interest to you that describes the effectiveness or cost-effectiveness of a clinical intervention or program in a human services sector. For suggestions or help in identifying articles, see the instructor or teaching assistant. For example, the instructor’s report, “Economic analysis of anti-viral therapy in Botswana” provides data on the cost-effectiveness of AZT for pregnant women. A copy is available on the web site under “downloads.” Two types of papers are possible. Alternative A: Perform a preliminary cost-effectiveness analysis. If the study is an effectiveness study only, perform a preliminary cost-effectiveness analysis. Clearly indicate the alternatives you wish to compare and the effectiveness measure, and provide illustrative results. Use existing data where readily available, and explicitly assume values for other the unknown data. Interpret the findings. Discuss what kinds of data would be needed to convert the preliminary study into a more valid cost-effectiveness study, and where would they be obtained? Which items do you think are most critical? 26

  27. Final Assignment of CE module, 2 Alternative B: Discuss a cost-effectiveness analysis. If the study is a cost-effectivenessstudy, discuss the appropriateness of the data, analysis, and interpretation, and put the results in a larger context. For example, compare the intervention under study with other interventions for the same disease or the same population. Submission: The length of the paper should be about 6 double spaced pages, including any tables or figures per student. Two or more students may work together and submit a joint paper that is proportionally more extensive, and longer if desired (6 pages per student). Please submit to Linda Purrini, administrative assistant, Heller G6, tel: 781-736-3930, Purrini@Brandeis.edu. Also, please include a copy a summary, abstract, or full copy of the article with your submission. The paper may also be submitted electronically to Ms. Purrini. Schedule: Due Thursday, Oct. 25, 2001 (10 days after the last class). Evaluation: The module will be graded according to each student’s registration (audit, pass-fail, or letter grade) based on this final exercise, other exercises, and class participation. In addition, the instructors plan to give written comments on this exercise. The instructors look forward to your papers. 27

  28. Final class session Monday, Oct. 15, 6 pm – 9 pm 28

  29. Final class, Oct. 15 • Help us identify illustrative, empirical, preferably intervention studies outside of the health sector • Collect and read the selected studies (distributed later this week) • Be prepared to discuss the cost-effectiveness framework: • What are the alternative(s)? • What are the costs? • What are the outcomes (effectiveness)? • How do we interpret cost-effectiveness results? 29

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