Essentials of pharmacoeconomics
You are interested in comparing the costs and outcomes over 1-year time period of preventive
strategies for postmenopausal women with osteoporosis. You plan to compare three options:
1) Oral Cal-More, 10 mg/day
2) Nasal Cal-More, 200 IU/day
3) Long-acting Cal-More, 70 mg once a week. (Note: These are not real product names.).
The main outcome measured is incidence of bone fracture and the effect on QALYs. Each year,
about 5% of the patients taking once-a-day oral Cal-More have a fracture (95% do not), about
10% of those taking nasal Cal-More experience a fracture (90% do not), and 5% of those taking
long-acting Cal-More experience a fracture (95% do not). The cost of treating a fracture is
$3,000, and a fracture decrease a person’s QALY by 0.5 QALYs. Once-a-day oral Cal-More
causes gastrointestinal (GI) complications in 5% pf the patients. Nasal Cal-More causes nasal
irritation or bleeding in 10% of the cases. Once-a-week oral Cal-More causes GI complications
in 2% of the patients.
The average cost of treating GI complications is $200, and QALYs are decreased by 0.2. the
average cost of treating nasal problems is $100, and QALYs are decreased by 0.1.
The costs per year of the three medications are:
• Once-a-day oral Cal-More = $600
• Once-a-day Nasal Cal-More = $800
• Once-a-week oral Cal-More = $1,000
1) Draw a decision tree (3 points)
2) Calculate path probabilities (1 Point)
3) Calculate the average QALYs for each treatment (1 Point)
4) Calculate the average cost for each treatment (1 Point)
5) Calculate the average cost per QALYs for each treatment (1 Point)
6) Calculate the ICER between treatment options oral once a day and nasal once a day (1
Point)
7) Calculate the ICER between treatment options oral once a day and oral once a week (1
Point)
8) Provide your conclusion (1 Point)
Sample Solution
Decision tree:
Start
/ | \
Once-A-Day Oral Cal-More Nasal Cal-More Once A Week Oral Cal-More
/ | \ |
Fracture No Fracture Fracture No Fracture Fracture No Fracture
(0.05) (0.95) (0.1) (0.9) (0.05) (0.95)
Path Probabilities :
Once – a – day oral cal more : 0 . 05 + 0 . 95 = 1
Nasal cal more : 0 .1 + 0 . 9 = 1
Once – a – week oral cal more : 0 . 05 + 0 . 95 = 1
Average QALYs for each treatment:
Once – A – Day Oral Cal More: For the 5% of patients that experience fractures, the decrease in QALYs is 0.5 per patient and for the 5% of patients that experience GI complications, the decrease in QALYs is an additional 0.2 per patient.
Thus, the average decrease in QALYs per patient on once-a-day oral Cal-More is ((5*0.5)+((100−5)*0)= 2.45).
Nasal Cal More: For the 10% of patients that experience fractures, the decrease in QALYs is 0.5 per patient and for 10% of those taking nasal Cal More who experience nasal irritation or bleeding ,the decrease in qalys is an additional 01 per patinet.
Hence ,the overall average reduction in qalys on nasal calmore will be ((10*05)+((100–10)*01)) = 5.
Once A Week Oral Call More :For the 5 %of patients experiencing fracture ,the decreased qalys is 05 whereas for those experiencing GI complication it’ll be 02.((5000+(1000–50)*02 )=3.
