Thursday, December 22, 2011

Rethinking Prescription Writing Standards (SIG)

So I train a lot of doctors on electronic medical records. I'm always interested to learn how doctors think about their medication orders. How do they write them? Do they understand them? Do they know who reads them? How does that order get to the patient?

One of the areas of prescription writing I'm particularly interested in is the SIG: section of a prescription. (For some of the basics of a prescription, see this excellent Wikipedia article.)

"SIG" is medical shorthand for "Signa", which in Latin literally means, "write". In simple English, it basically means, "Please write these instructions for taking the medication : _________________"

(Huh? Why not just write "Instructions : _____________" - I mean, don't we have printed pads? Is ink too expensive?)

Anyway, some examples of "SIG:" shorthand commonly seen on prescriptions include :
SIG : 2 tabs PO q6h prn   (IN ENGLISH : Two tablets by mouth every six hours as needed)
SIG : 40 mg PO BID  (IN ENGLISH : Forty milligrams by mouth twice daily)
SIG : 1 patch TD daily (IN ENGLISH : 1 patch topically daily)

Why do doctors write this bizarre latin shorthand? I'm not sure, but it sure is short to write. For more details on this medical shorthand, Wikipedia has this article on prescription shorthand - Some of these I'm not even familiar with as a practicing physician.

Does this shorthand help patients understand how they're supposed to take their medications? Not really. So we need pharmacists and nurses and other health professionals who help interpret this.

As a linguist, I'm also puzzled - Here we have a writing that allows communication from doctor to pharmacist, and doctor to nurse, but not doctor to patient. Why does this language exist?

One of the more fascinating parts about this communication is that here seems to be some confusion about "BID", "TID", "QID", etc. versus q12h, q8h, and q6h.

First, some background about this :
  1. QD - In Latin : Quaque Die - In English : means "Once a day"
  2. BID - In Latin : Bis In Die - In English : means "Twice a day"
  3. TID - In Latin : Ter In Die - In English : means "Three times a day"
  4. QID - In Latin : Quater In Die - In English : means "Four times a day"
These are so pleasant, and potentially difficult to read (depending on handwriting), that they are falling out of favor and being replaced with their English equivalents.

Then, there is the q___{time} designation, like :
  1. q2h = Every 2 hours
  2. q4h = Every 4 hours
  3. q6h = Every 6 hours
  4. q8h = Every 8 hours
  5. q12h = Every 12 hours
  6. q24h = Every 24 hours
  7. q48h = Every 48 hours
What I find interesting is the common question, "Should I write this medication QID or q6h?"


Ever heard of the story of the patient who asks the pharmacist, "My doctor says I should take this medication four times a day - Does that mean I need to wake up in the middle of the night to take it?"

What this speaks to is some confusion about the difference between the two. Often, doctors use the two interchangeably. But while in most patients the clinical difference is minimal, they are very different to nurses and pharmacists. Here it is :

QD, BID, TID, and QID actually have very specific times attached to them.
  1. QD = usually 08:00am
  2. BID = usually 08:00am and 20:00pm
  3. TID = usually 08:00am and 12:00noon and 20:00pm
  4. QID = usually 08:00am and 13:00pm and17:00pm and 22:00pm
When I say usually, I mean it - Many hospitals have slight variations to this schedule. As an example of how challenging this can be, some hospitals publish their own standard medication timing guidelines like this which try to help standardize these times. Ask your hospital pharmacy what their standard med administration times are!

The one thing that is pretty standard about all of these (QD, BID, TID, QID) in virtually all hospitals is that, as much as they might vary, they're all usually during waking hours. None of them would technically let you take a dose at 4am.

q2h, q4h, q6h, q8h, q12h - DO NOT have specific times attached to them.

In other words, if you write to give a medication every 12 hours, the actual time it will be given will depend on what time you write the order : If you write it at 5am, then the medication will be given at 5am and 5pm. If you write it at 7am, then the medication will be given at 7am and 7pm.

Of course, if you wanted it to be given at 8am and 8pm, but you were writing the order at 5am, then you could write "q12h START TIME : 08:00am

This is why it's not uncommon to see as-needed pain medications written as "TID PRN" - Many doctors are not even totally aware of the difference between TID and q8h. Of course, in most of these instances, if a patient were to go to the doctor and ask "Can I take it at 4am for pain if I need to?", the doctor would often say "yes".

Clear as mud? The good news is that with most medications, being an hour or two off means little in terms of the amount of drug in the blood - So it really doesn't make much difference from a clinical perspective. 

But this language sure causes some confusion. Do we really need this Latin shorthand? Who is it helping?


So today at work, I was rethinking the sig :

And it's interesting - I noticed that in about 90% of prescriptions :
  1. PRN (as needed) medications : Often use q____h PRN _________________
  2. Standing (regular) medications : Often use QD, BID, TID, QID
This makes sense - Generally, docs don't want their patients waking up regularly to take medications at 3:00am.

So I wondered : Could we leverage this pattern to help with electronic order entry?

And then I wondered : Instead of this alternate, Latin-based language which allows doctor-to-nurse and doctor-to-pharmacist communication, but no doctor-to-patient communication ...

could we make a language that everyone (doctor, patient, pharmacist, and nurse) understood equally well?


It seems the real division is between regular (every day) medications and PRN (as needed) medications.
As I mentioned :
  2. AS NEEDED (PRN) : COMMONLY USE Q___h PRN ____________
So could we use this to shorten the length of options commonly seen in EMRs for medication frequencies?

And then when doctors, nurses, and hospitals are trying to collect medication histories with the simplest, smallest number of clicks, instead of thinking of :
[ Medication Name ] [ Dose ] [ Route ] [ FREQUENCY ] [ PRN ] [ REASON ] 
could we instead cognitively think about medication orders like this :
[ Medication Name ] [ Dose ] [ Route ] [ PRN ] [ FREQUENCY ] [ REASON ] 

This would allow us to re-consider, re-evaluate, and redesign our forms!


And so a draft paper form could potentially look something like this :

And this would allow us to set up the electronic documentation of a single medication according to this form where you could "just click on options" :

And so for about 95% of medications, this would allow you to enter medications very easily! For example, Lasix 40mg PO BID could instead be : ("Lasix 40mg" + 3 clicks)

Or Percocet 5/325mg PO q6h PRN moderate pain (4-6) could be : ("Percocet 5/325mg" + 2 clicks + "moderate pain") :

Or one could even expand the PRN reasons, to turn that same percocet order into "Percocet 5/325mg" + 3 clicks) :

and this could be a form that physician, pharmacist, nurse, and patient could easily comprehend to all speak the same language.

It also guides a physician to avoiding the small issue of "Percocet 5/325mg PO TID PRN mild pain".

And for those other 5% of medications where either there are unique medication times, or when you absolutely need the patient to take the medication every 6 hours and start at 03:00am, you could still click the "FOR OTHER INSTRUCTIONS" box all the way at the right.

I just thought I would share some ideas of how you can help fix your med reconciliation forms and possibly your med reconciliation EMR software, to promote clarity and help reduce clicks. Who knew medical informatics could be so much fun!

Would love comments! Anyone have any other thoughts about the subject? As always, education is a priority, and discussion is welcome!


diananicolenow said...

I really found this article interesting as I was just recently accepted into pharmacy school and was studying up on my sig knowledge. Recently, I was given a typical prednisone script for an allergic reaction. As the days continue, the dosage tapers off. The RX stated TID, BID, QD. Of course initially, I started doing all the math and over thinking it, and it made me more aware in a real world way of exactly what your article discussed. TID, BID, & QID aren't always the same as Q8h, Q12h! Appreciate the thoughts!

diananicolenow said...

I really found this article interesting as I was just recently accepted into pharmacy school and was studying up on my sig knowledge. Recently, I was given a typical prednisone script for an allergic reaction. As the days continue, the dosage tapers off. The RX stated TID, BID, QD. Of course initially, I started doing all the math and over thinking it, and it made me more aware in a real world way of exactly what your article discussed. TID, BID, & QID aren't always the same as Q8h, Q12h! Appreciate the thoughts!

Woedendenaar said...

As a patient: what the doctor *tells* me to do supercedes the label on the medication. Obviously this isn't ideal, but there are meds that have nonsensical instructions on the label to get around the insurance company's meddling in my treatment, decisions that were clearly *not* made in my best interests. My doctor, my pharmacist, my wife, and I know how I'm really taking them.

Example: decided I only 'need' a half dose of the antidepressant that literally saved my life. Under my doctor's care, we tried that - we always try to reduce prescriptions to the minimum effective dose - and confirmed what we already knew: that the dosage he prescribed, after 18 months of testing various other dosages, twice what the decided I 'need', is where I am supposed to be. says 300mg qd is too much, so he changed it to 150mg bid, with the understanding that I actually take them both at the same time. He knows it's ridiculous, I know it's ridiculous, but neither of us make the rules. (Sadly. I'd prefer my medical care decisions be made by the doctor I've been seeing for 20 years, rather than random reductions whenever the decides they want more money.)

~1975 I asked my (then-)doctor, who had delivered both me and my father, why the prescriptions he wrote were so cryptic. He said the point was to make it clear to the pharmacist, *not* the patient, because patients who understand what is written sometimes try to modify (or forge completely) their prescriptions. This was in pre-computer days, back when doctor's offices were somewhat routinely broken into by people wanting to steal blank prescription pads.

Richard said...

When using 'military' time it is improper to use clons. 8PM is properly written 2000 hours. Moreover it's redundant to say 2000PM, there is no such thing as 2000AM, 2000 can only ever be PM.

LeaJ said...

I'm pretty sure that mistake was made by the author, who generally uses military time, trying to write in am/pm so the reader would understand and he just got them mixed up. Like someone who's a native Spanish speaker reverting back from English on occasion. All of us in the medical field, author included, are very proficient at using military time. It's one of those things you learn on the third day of class, not its own subject to be mastered. I could teach my 4 year old military time in a day.

LeaJ said...

I'm sure the MD knows the proper way to use military time. It was probably a dictation error. I could teach it to my 3 year old. But thanks for the explanation.