When assumpions become "facts"

The post for this week was supposed to be a rant against rising drug costs.  Here's how far I got before realizing that I should get some specific data to make my points more convincing:

Back rounding with the inpatient resident service recently and, yet, again, I was irritated by the widespread use of Zofran in our hospital.

Let's back up.  Zofran's been around since 1991 in the US.  Researchers developed it to treat chemotherapy-induced nausea and vomiting.  Because Zofran rarely causes any untoward side effects, it became a popular anti-emetic for non-chemo related nausea and vomiting as well.

The older antiemetics, Compazine (prochlorperazine) and Phenergan (promethazine), work great for most nausea and vomiting but didn't perform as well for chemotherapy-related n/v.   They also can also infrequently cause unpleasant extrapyramidal side effects (acute dystonic reactions, akathisia, tardive dyskinesia) along with, rarely, cardiac arrhythmias.

When I was a resident, I remember well the experienced Emergency Department physicians that I rotated with.  "I don't know what's wrong with good old Compazine," one would frequently say.  "Sure, it can rarely cause bad stuff.  But most of the time it doesn't.  And it's a helluva lot cheaper."

So, I e-mailed some of the pharmacists that work at our hospital, asking for the costs of one dose of each of those three medicines.  All I needed to finish off the post was to plug in those costs and let my readers be outraged at the widespread use of the extremely expensive Zofran versus its cheaper counterparts.  Another couple of lines about cost-control in medicine and - voila! - post completed.

Except that my friendly pharmacists e-mailed back to let me know that all three of those meds cost about the same; one IV dose of any of them costs between $1.00 to $1.50.

Oh. 

(Insert picture of me eating humble pie here.)

So much for the rest of that post!

Turns out what I thought was "fact" was totally incorrect.  Yet I have been railing against the spread of Zofran use in our hospital since starting as an attending there nearly three years ago. 

"We, as physicians, are largely responsible for rising health care costs," my diatribe to the residents would begin.  "Why are we using Zofran, an expensive drug for cancer-induced nausea, for an otherwise healthy 25-year-old with viral gastroenteritis?  There are less expensive options that are reasonable to use, yet somehow Zofran has become the de facto antiemetic around here!"

Shame on me, for treating my assumptions as facts.  When Zofran first came out, it probably was more expensive.  But that was several years ago, and I never bothered to update my thinking.  We do that frequently in medicine - tout our biases and thinking as irrefutable facts - but those examples can wait for another day.  For now, I need a glass of milk to wash down this humble pie. 

And one dose of Zofran for the post-pie dyspepsia, please.