Case Study: QALYs

NoneIntroduction and Learning Objectives

By the end of this session, participants will be able to:

  1. Define and parameterize key inputs (e.g., probabilities, outcomes, and costs) within the Amua software.

  2. Evaluate model outcomes, such as expected quality-adjusted life expectancy (QALE), for alternative clinical strategies.

Decision Trees

Add QALY Dimension

We now want to add a new outcome dimension: QALYs (Quality-Adjusted Life Years). QALYs are a measure of disease burden, where 1 = perfect health and 0 = death.

Instructions:

  1. In Amua, go to Model → Properties → Analysis tab.

  2. Add a new dimension:

    • Dimension: QALE

    • Symbol: Q

    • Decimals: 2

  3. Click Refresh

  4. For QALYs make sure the objective is maximizing

  5. We can now return to the tree and enter QALE values at each terminal node

Clinical State QALE Notes
QALE_Untreated 3.21 Large amounts of time at low quality of life
QALE_SickTreated 14.54 Short amounts of time sick and in treatment
QALE_Healthy 20 Full Health
QALE_HealthyTreated 19.432 Very short amount of time in treatment

You can apply these QALE values to terminal nodes in Amua accordingly. Your tree should like this:

Now, you’re ready to perform a cost-effectiveness analysis with QALYs as the outcome!

Click Run Model and check out the CEA Results report.

Markov Models

Add a QALE Dimension

We now want to add a new outcome dimension: QALE (Disability-Adjusted Expectancy). QALYs, where 1 = perfect health and 0 = death. For this model, we will add Years of Life Lost. To discount these from the start of time and the time of occurrence we will use the built in discounting (from start time) and add discounting from the time of death.

A: Important Parameters

Quality of Life Adjustments

Name Value Description
u_healthy 1.0 Quality-of-life (QoL) weight for healthy state.
u_treatment 0.932 Quality-of-life (QoL) weight for healthy state.
u_sick 0.842 Quality-of-life (QoL) weight for sick health state.
u_sicker 0.645 Quality-of-life (QoL) weight for sicker health state
u_dead 0 Quality-of-life (QoL) weight for death health states.

Add QALYs

A: Add A QALY Outcome

  1. In Amua, go to Model → Properties → Analysis tab.

  2. Add a new dimension:

    • Dimension: QALE

    • Symbol: QALY

    • Decimals: 2

  3. Click Refresh

  4. Change the “Analysis Type” to Cost-Effectiveness Analysis (CEA).

  5. Set the Cost, Effect, Baseline Strategy and Willingness-to-pay (WTP). Ensure that the Effect Objective is still set to mazimize.

  6. Go to the Markov tab and add in the discount rate for DALYs. (3.0)

B: Add QALY to the model

  1. Next, in the model itself, define the cycle-specific payoffs based on the values in the table above.
![](images/QALYs/TreatNoneQALYs.png){width="555"}
  1. Repeat the same thing with the Treat All branch. BUT also add a one time utility for treatment

Check and run the model to get the CEA for QALYs

Strategy Cost QALE ICER Note
Treat None 40,286.24 14.8198 Baseline
Treat All 51,548.10 17.6283 4009.9429

Solution File:

What if there are multiple disability weights in one state?

For Example: Suppose you can get AD heart failure and Stroke in one state.

There are multiple ways to handle this: Joint Utility Methods Slides