Statistics and health technology assessment

1. Intro to Health
Technology
Assessment
Cathal Walsh
Centre for Health Decision Science (HRB)
@CHeDS_ie
Biostatistician (NCPE) - Chair of Statistics (UL)

2. Decision Making
Question
Information Values
A set of
recommended
treatments

3. Health Technology
Assessment
• In theory, HTA provides a structured
framework for decision making.
• The framework used in Ireland is similar
to that employed in the UK and uses the
QALY and cost tradeoff.

4. Decision Making … the QALY
• The quality adjusted life year (QALY) is a
function of quality and duration of life.
This is best illustrated by a sketch …
• Note that it explicitly trades side effects,
disability and inconvenience of treatment
(etc!) against outcomes.

5. Tx 1 (Sustained)
Tx 2 (+efficacy, waning.)

6. Notes on the QALY
• In theory we can compare in an
equitable fashion across disease areas.
• This allows consideration of the impact
of interventions in a fair way and in a
univariate fashion.
• Thus a perfect ranking of interventions
can be obtained.

7. Decision Making - the C/E
plane
• The cost effectiveness plane is a core
aspect of how outcomes are
communicated and interpreted. It trades
off gains in health outcomes (on the x-
axis) and costs (on the y-axis).

8. Simple Decisions ... ?
*
++ Health
++ Investment
*
**

9. Simple Decisions ... ?
(Q,C) Do It
++ Health
++ Investment

10. Simple Decisions ... ?
(Q,C)
Don’t do It

11. Simple Decisions ... ?
(Q,C)
Put it on the
list of things to
do …

12. Simple Decisions ... ?
(Q,C)
Put it on the
list of things to
do …
ICER

13. Simple Decisions ... ?

14. Simple Decisions ... ?

15. Simple Decisions ... ?

16. Simple Decisions ... ?

17. Simple Decisions ... ?
*
++ Health
++ Investment
*
**

18. The Threshold … The Theory
ICER < 45k / Q good
ICER > 45k / Q bad

19. Simple Decisions ... ?
*
++ Health
++ Investment
*
**

20. The Threshold … The Theory
BUT … why use 45k?

21. The Threshold … The Theory
Utilisation
ProspectiveThreshold

22. The Threshold … The Theory
Utilisation
ProspectiveThreshold

23. The Threshold … Estimation in Practice
• What is the cost per QALY of the things
we stop doing to afford the new things?
• What is the cost per QALY of the things
we should stop doing to afford the new
things?
• On average, what is the marginal cost
per QALY in our health system?

24. The Threshold … Estimation in Practice
• What is the cost per QALY of the things
we stop doing to afford the new things?
• What is the cost per QALY of the things
we should stop doing to afford the new
things?
• On average, what is the marginal cost
per QALY in our health system?
Inefficiencies
Disinvestment
Practical Assessment
(Data?!)

25. Other considerations
• The Value set we use.
• The Uncertainty associated with the
parameters.
• The comparators used in the models.
• Indications for treatment.
• Structural uncertainty in models.
• Societal vs healthcare payer perspective.

26. Workarounds (Fudges)
• QALY loadings.
• Disease specific threshold.
• Selective alternative perspectives.
• Ring fenced budgets for selected
conditions.
• Differential discounting.
• MCDA (perhaps?).

27. Multi Criteria Decision
Analysis
• Affects the Value side alone.
• Allows explicit incorporation of other
factors into the value function.
• Strictly speaking cost per QALY is a form
of MCDA.
• Cannot change the budget available –
just the ordering of the interventions we
fund.

28. What do we do now?
• An ‘informal’ MCDA approach.
• A 45,000 / QALY ‘initial’ threshold.
• Reimbursement occurs for some
interventions above this level.
• A process for broader consideration of
the decision exists.

29. Exercise