How to evaluate the economic impact of influenza II: Methods and cost-effectiveness

Transcription

1 Workshop on Health and Economic Impact of Influenza, Indonesia, 5-7 June 2012 How to evaluate the economic impact of influenza II: Methods and cost-effectiveness Mark Jit Modelling and Economics Unit Health Protection Agency United Kingdom I have no conflicts of interest to declare.

2 Why cost-effectiveness? Picture credits: John A Bannes Elementary School, Tinley Park. Dottie McDowell, teacher. Samantha C, 4th grade. From the Illinois Council on Economic Education annual poster award winners. Used with permission.

3 What is cost-effectiveness A cost-effectiveness analysis compares the incremental costs and consequences of an intervention compared to a comparator Costs Disease burden Costs Disease burden Option B Option A

4 Cost-effectiveness analysis Cost of intervention (eg. vaccination) - Cost savings due to intervention Beneficial effects of intervention = $ per unit of effect Measured in quantities like: episodes of flu prevented life years gained QALYs or DALYs gained C DB Option A C DB Option B

5 Turner et al. Health Technol Assess 2003; 7(35). Cost-effectiveness acceptability curves Cost-effectiveness acceptability curves for three antivirals used for treating influenza Country Decision making body Willingness to pay for a QALY Australia PBAC A$30,000-A$50,000 Netherlands CVZ 20,000 UK NICE, JCVI 20,000-30,000 USA ACIP $50,000 - $100,000 Global WHO 1-3 x GNI per capita

6 Requirements for a cost-effectiveness analysis Cost of illness Cost of vaccine (purchase + delivery) Budget impact analysis Epidemiological burden Economic burden of disease Vaccine impact (direct +indirect) Micro-economic evaluation (CEA, CBA) Macro-economic equilibrium state Macroeconomic evaluation

7 Types of economic models Static model S Susceptible I Infected R Recovered Dynamic model S Susceptible I Infected R Recovered

8 Vaccine impact: ecological (herd) effects The basic reproduction number, R 0 Population with R 0 of 4

9 Vaccine impact: ecological (herd) effects Population with R 0 of 4 and 50% vaccine coverage, so R n is 2

10 Vaccine impact: ecological (herd) effects R 0 and the herd immunity threshold Polio Influenza Measles SARS

11 Vaccine impact: ecological (herd) effects Results from clinical trials Household study: Reduction in influenza-related outcomes in household contacts of children 2-5 years old vaccinated with TIV Esposito et al. Vaccine 2006; 24:629

12 Cases prevented per 100 people Vaccine impact: ecological (herd) effects Transmission dynamic modelling Clinical influenza cases prevented by the English influenza vaccination programme (Vaccination targets adults 65+ years and those in clinical risk groups) Direct Indirect < Baguelin et al. Vaccine 2012; 30:3459

13 Vaccine impact: ecological (herd) effects Transmission dynamic modelling S E I R Susceptible Latent Infected Recovered (t) = S(t) I(t) Adapted from Newall et al. Emerg Inf Dis 2010; 16:224.

14 Existing seasonal influenza vaccine policies Source: WHO seasonal influenza survey 2010, 193 WHO Member States. Data as of February 2011 Countries which data are currently not available and pending on the new regional survey in 2011 Countries offer seasonal influenza vaccination not in national programme but in private sector Acknowledgments to Janna Klein Breteler for this slide. Countries with seasonal influenza vaccination in national vaccination programme in 2010 Countries without seasonal influenza vaccination in national programme Countries plan to have seasonal influenza vaccination in national programme by 2012

15 Existing seasonal influenza vaccine policies Priority Subsidized Priority Subsidized Countries Countries Age (year) Role/occupation Health care worker Care home resident Animal contact Close contact Care home worker Essential community service 7 5 Medical condition Lab worker 2 1 Chronic illness Traveller 1 1 Pregnant Teacher 3 2 Disabled 1 2 Aboriginal 3 1 Obese 9 7 Financial need - 2 Universal - 3 Ng et al. BMC Infect Dis 2011; 11:230.

16 Potential target populations Children (0-5 year olds or up to school age) Main transmitters. Societal cost of productivity loss for caregivers. Had higher risk of complications to 2009 pandemic strain. Clinical risk groups (any age) Immune compromise, asthma, pulmonary disorders etc. which raise risk of complications due to influenza. Health care workers (any age) Elevated risk of infection. Risk of transmission to patients. Older adults (50-64 year olds) Elevated risk of complications, hospitalisation and death. Many still working so productivity cost to illness. Elderly (65+ year olds) Highest risk of complications, hospitalisation and death.

17 Review paper Target group Studies Conclusions Burls et al. Vaccine 2006; 24:4212 Gatwood et al. Drugs 2012; 72:35 Newall et al. Pharmacoeconomics 2009; 27:439 Newall et al. Pharmacoeconomics (in press) Savidan et al. Health Policy 2008; 86:142 Results of economic models Seasonal influenza vaccination Health care workers Working adults year olds 2 studies + 1 de novo analysis All cost saving 7 studies 2/7 cost saving 6 studies 1/6 cost saving Children 20 studies 13/20 cost saving Children 15 studies 9/15 cost saving NB: Literature review by WHO (Klein Breteler et al.) found only 4 full economic evaluations of influenza vaccination in LMICs; all 4 were in upper middle income countries.