Hi Roberto, If you are asking about the calculation of the index you can obtain value sets and code for multiple statistics software packages on their website. If you see differences in your baseline index you may want to adjust for these differences statistically in your QALY calculation.

http://www.euroqol.org/about-eq-5d/valuation-of-eq-5d.htm

Hi Bryce. Thanks for your answer. I have a tool (excel) to calculate the index of EQ-5D (the utilities, a number from 0 to 1). But my question is about how calculating the QALYs using these utilities, to make a cost-utility analysis. The most commonly used formula is QALYs = U x t

U is utility (extracted from the EQ-5D)

t is time (in years) that the patient is in that utility.

But I need calculate it for a short period (4 months), and 3 sampling times (pre, during, post = 0 months, 2 months, 4 months).

I do not know if I explain well...

Thank you very much.

Hi Roberto,

Just adjust the t to a percentage of the year. So for your 2 months it will be 0.167 and 4 months will be 0.333. Your pre intervention data will be the baseline.

best wishes,

Agi 

Thank you very much Agi.

Then (last question), to know the QALYs during the first 2 months (for example), if I do the mean of the utilities between month 0 and month 2, would be correct?

In that example:

U mean first 2 months = (U month 0 + U month 2)/2

U mean first 2 months x 0.167 = QALYs in first 2 months

Would be correct?

Any reference to cite?

Many thanks!

Yes that is correct, then repeat that calculation for 2 months to 4 months, noting as Agi indicated that your maximum qalys over the observation period would be 0.333.  You probably don't need to cite this but if you want to be thorough it's sometimes called the trapezoidal rule for area under the curve.  You'll find it in most books on economic evaluation in health care.

Bryce and Agi, your answers have been a great help!

Thanks a million!!!

Hi Roberto,

One other thing to consider - plot all of your individual QALYs to observe the distribution first. If you have skewed data (i.e. your distribution is not centred) then use the median rather than the mean for your QALY value. You can also explore this choice (median vs mean) in a sensitivity analysis.

Reference for this:

Dolan, P. (2000). Chapter 32: The measurement of health-related quality of life for use in resource allocation decisions in health care. Handbook of Health Economics. 1 (B) p1723-60.

Best wishes,

Agi 

Many thanks for the reference, Agi!

It will be very usefull.

Regards.

Roberto.

I have a follow-up question: If you want to compare two different interventions (A and B) for instance in a cost utility analysis. Do you simply subtract?

QALYs (A) - QALYs (B) = (U mean (A) x t) - (U mean (B) x t) ?

Best regards

Håvard

Dear Håvard.

First of all, Sorry for the late answer.

Regarding your question, I think that your solution could be good, but I can not say for sure.

When you do that, maybe you could convert that difference in %. In this way, you will be able to show what is the percentage of improvement of one intervention against the other. I think it could be a very useful information.

Best regards.

Roberto.

Dear Roberto!

Thanks for your reply!! I see it's a good idea to present the percentage.

Best regards

Håvard

can we use EQ VAS for calculating QALYs

Nousheen Aslam, VAS are not commonly included in QALY analysis

HI, the nearly same question is that If I have mean scores of SF-36 from previous publication, how can I estimate QALY from these mean scores?

Thank you so much

Hi Theresa, You can applied a mapping algorithm validated by the peer-reviewers.

This reference could be an example : Franks, P., Lubetkin, E. I., Gold, M. R., Tancredi, D. J., & Jia, H. (2004). Mapping the SF-12 to the EuroQol EQ-5D Index in a National US Sample. Medical Decision Making, 24(3), 247–254.

Imad el Badisy Thank you for your information so much. It is very helpful!!!

I have a followup question. In order to get Utility Value from EQ5D, we use EQ5D TTO values in Index calculator.

I belong to Pakistan. I want to know which country's Index calculator should I use as Pakistan Index calculator of EQ5D is not available till date?

Hello Mohsin Hassan Alvi ,

This could depend on several parameters. For example, the life expectancy of the general population, the health system, the standard of living, the shared culture...etc

Simply put, it is necessary to find a country with similar socio-demographic characteristics, with available EQ-5D data and validated mapping algrothim.

I hope this will help you.