You're a member on the local Pharmacy and Therapeutics committee. A new drug request is presented to the committee requesting the addition of a new biphosphonate for osteoporosis and prevention of hip fractures in post-menopausal women.

The drug cost per tablet is a little bit less than your current formulary biphosphonate. The side effect profile is the same or maybe a little bit better for the requested drug vs. the formulary drug. The number needed to treat (NNT) for each drug to prevent one hip fracture is 90.

Lifetime risk of hip fracture in women is 15%. Hormone replacement therapy is questionable. Other hip fracture prevention therapies have their risks as well. This drug is new and getting a lot of media attention and direct-to-consumer advertising. Many providers in your area and in your hospital are using it in moderate to high-risk women and you've been asked
by a number of women to prescribe this for them.

Do you vote to add the drug to formulary or not? Why or why not?

** Many Thanks to Ms Sheri Strite and Dr Mike Stuart from The Delfini Group, www.delfini.org, an evidence based medicine consulting firm, for help with this Pearl **
 

Hmmmm .... Add to formulary? Although this decision sounds like a "no-brainer", it may not be. You need to ask some more critical questions. See the discussion and illustration below.

The key here is the NNT. The NNT is calculated by dividing 1 by the absolute risk reduction (ARR) [NNT = 1/ ARR]. The other key is HOW LONG was the treatment needed to produce the NNT for the various products.

In our example, the NNTs were the same but the duration of the studies were different. The study duration for the formulary drug vs the requested drug were 2.9 years and 5.0 years, respectively. Based on these therapy durations, you need to treat a patient with the requested drug for almost TWICE as long (5.0 years) to prevent ONE hip fracture, compared to the current formulary drug (2.9 years).

A financial illustration using these NNTs and duration of therapy -
Assumed drug costs (your costs may vary)
Formulary drug - $1,000/year    NNT=90    Duration of study = 2.9 years
Requested drug - $ 900/year    NNT=90    Duration of study = 5.0 years

Estimate 2,500 women at high risk for hip fracture
Formulary drug = $1,000/year * 2,500 women = $ 2,500,000
Requested drug = $  900/year * 2,500 women = $ 2,250,000 (An apparent $250K annual cost avoidance?!?!)

Annual cost per hip fracture avoided
Formulary drug
$ 2,500,000 - drug cost per year (est 2,500 high risk women * $1,000/year)
2,500 high risk women / 90 (NNT) = ~ 28 fractures prevented in 2.9 years
28 fractures / 2.9 years = ~ 9.65 fractures prevented in ONE year
$ 2,500,000 / 9.65 fractures per year prevented = $ 259,067 per fracture prevented

Requested drug
$ 2,250,000 - drug cost per years (est 2,500 high risk women * $ 900/year)
2,500 high risk women / 90 (NNT) = ~ 28 fractures prevented in 5.0 years
28 fractures / 5.0 years = ~ 5.6 fractures prevented in ONE year
$ 2,250,000 / 5.6 fractures per year prevented = $ 401,785 per fracture prevented

The cost for EACH fracture prevented using the new drugs is $ 142,718 ($401,785 - $259,067 = $ 142,718). If these figures hold true for your institution or practice, you should NOT add the drug to the formulary.

This Pearl is meant for academic and educational purposes only. This Pearl is meant to raise important points regarding the safe and cost-effective pharmacotherapy of patients. It is not meant to be the definitive reference for the treatment or prophylaxis of various diseases. Although every effort is taken to ensure this Pearl is correct and factual, errors may occur. The Pharmacoeconomic Center assumes no liability for incorrect information or harm that may occur from the use of the information included in this Pearl.