Download Appendix A: General Scheme of a Cost Utility Analysis Economic

Appendix A: General Scheme of a Cost Utility Analysis
Economic
Evaluation Steps
1. Ask a clear
study question
2. Determine
perspective to be
used
3. Calculate direct
costs associated
with the two
procedures
4. Review
literature to
identify all
complications
(health states)
associated with
these procedures
and treatment of
these procedures
5. Identify the
probabilities and
cost of each
complication
6. Design a
decision tree with
branches showing
health states and
the probability of
each
7. Measure utility
and QALY for
each complication
pathway
Example
What is the more cost-effective procedure: the Deep Inferior
Epigastric Perforator Flap (DIEP) or Free Transverse Rectus
Abdominis Myocutaneous (TRAM) Flap for postmastectomy
reconstruction?
Third-party payer (Ministry of Health for Ontario)
Direct medical costs taken from the third-payer perspective
(surgical fees, anesthetist’s fees, hospital charges) from the
Ontario Ministry of Health Schedule of Benefits
For example, total/partial flap failure, hernia, abdominal wall
weakness, fat necrosis, hematoma as well as the health state of
“successful surgery”.
For example the expected cost of for a hernia: 0.2 (probability of a
complication occurring) x 0.04 (probability of a hernia occurring)
x estimated cost ($1663.48) to give an expected cost = $13.31
(costs derived from the Ontario Ministry of Health Schedule of
Benefits).
Examples of two decision trees:
To determine utilities of various health states associated with
DIEP and free TRAM flaps, 32 plastic surgeons across Canada
were asked to rank their preference using a ‘feeling thermometer’
(10 cm vertical ladder with 0 = death; 1 = perfect health).
Successful surgery was determined to have a utility of 0.87.
QALY was calculated using a hypothetical patient of 45 years with
life expectancy of 78.6 years (statistic from Statistics Canada).
QALY (complication) = [(duration of health state) x (utility of
health state)] + [(# healthy years remaining – duration of health
state) x (utility of successful breast reconstruction)]
For example using hernia as the complication:
= (0.31* x 0.66**) +((78.6 – 45 years) x 0.87)
= 29.17
8. Calculate
expected cost and
expected QALY
for each
comparative
intervention
9. Calculate ICUR
and find if it falls
within the
acceptability
threshold
10. Perform
sensitivity
analysis to see if
the results are
robust
Please see Thoma & McKnight16 for more information.
Utilities, Costs (CDN $), QALY of all Health States
Use the equation:
ICUR = (Mean CostDIEP – Mean CostTRAM)____
(Mean QALYDIEP – Mean QALYTRAM)
Please see Thoma & McKnight16 for more information.
Cost-utility Analysis: Baseline and Sensitivity Analyses
Comparing Free TRAM and DIEP Flaps
* 0.31 was determined by number of weeks/year = 16 weeks/52 weeks = 0.31 years
** 0.66 was the utility of health state determined from the vertical feeling thermometer
from the 32 plastic surgeons
Table adapted from: Thoma A, Veltri K, Khuthaila D, Rockwell G, Duku E. Comparison of
the deep inferior epigastric perforator (DIEP) and free transverse rectus abdominis
myocutaneous (TRAM) flap in post-mastectomy reconstruction: A cost-effectiveness
analysis. Plast Reconstr Surg. 113: 1650, 2004