Using QALYs in costeffectiveness analyses: Methodological and conceptual challenges

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Using QALYs in cost-effectiveness analyses
Methodological and conceptual challenges

• Radek Wasiak, PhD
• Radek.Wasiak_at_unitedbiosource.com

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Outline

• QALY and its rationale
• Issues with using the cost/QALY ratio
• Implications for decision-making

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QALY and its rationale

• Quality-adjusted life years (QALY) a common
  unit for valuing health effects of health care
  interventions
• QALYs used rather than costs due to sensibility
  of valuing health in monetary units
• QALYs combine the life expectancy with average
  predicted quality of that life
• Assumes that the aggregate accurately reflects
  the value of health effects

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Arguments for using QALYs

• Avoids directly valuing health in any currency
• Fits with the utilitarian view that the purpose
  of any health care system is to maximize total
  health of population
• Easy to implement in decision-making
• Obtain most QALYs possible given the existing
  budget

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Methodological issues with QALYs

• Many brought up, in particular the quiet
  arbitrary nature of assigning quality of life to
  each health state
• For discussions see
• Gyrd-Hansen Pharmacoeconomics 2005
• Duru et al. Pharmacoeconomics 2002
• McGregor CMAJ 2003
• Nord, 1999
• Proponents argue that no better instrument exists
  so we should use QALYs until a better one is
  found and aim to improve it

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Conceptual problems with QALYs

• QALYs can be unethical
• QALYs rely on assumption that value of human life
  depends on its duration and quality
• Can lead to discrimination according to patients
  characteristics
• Example1 ceteris paribus, health intervention
  helping 40 year-olds will be more cost-efficient
  than 50 year-olds because of slightly longer life
  expectancy
• Similar penalties gender, race, obesity,
  disability, poverty, residential location
• Example 2 ceteris paribus, health intervention
  helping those with no underlying chronic health
  problems will be preferred
• Sample penalties mental health problems, asthma,
  physical dysfunction all associated with
  diminished quality of life
• QALYs do not reflect social values
• QALYs value identically improvement from 10 to
  35 in quality of life to that of 75 to 100
• Societies tend to believe that sicker patients
  should receive priority
• QALYs prefer health conditions for which quality
  of life improvements can be made with health
  interventions
• Societies tend to believe that all patients
  should have same access to care regardless of
  their illness

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Impact on decision-making

• Use of cost/QALY ratio assumes that the goal is
  to maximize total health across society
• The idea is that with limited budgets, only a set
  of interventions can be provided and a decision
  tool is necessary in order to do that fairly
• Typically, an efficiency threshold is used
  anything below is approved, anything below is
  rejected as not cost-effective.
• But given the conceptual challenges, what is the
  alternative?
• Use available evidence to estimate health
  benefits and net costs of the intervention
• Consider additional investments entailed if
  intervention should be reimbursed/used (i.e.,
  opportunity cost)
• Should be assessed at total levels not at per
  patient basis

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• Questions or comments?