Why Evidence-Based Medicine is a Challenge

We physicians all like to think we practice evidence-based medicine (EBM).  After all, that’s what separates us from chiropractors, homeopaths, and the other assorted “specialists” out there offering medical advice.  The truth of the matter though is that we fall short of that lofty goal for three reasons. 

The first is the difficulty in keeping up with the latest cutting edge data. How many medical journals are published every month? Even if you just read the abstracts in your field, you wouldn’t have any time to see patients.  Moreover, sometimes you have to “unlearn” what was felt to be EBM when new evidence comes out refuting previous studies.  I remember hearing from a pediatric dermatologist recommending the use of Aldara on molluscum, off label of course.  Only later does a study come out showing it is not effective on molluscum.

A second reason we don’t always practice EBM is that we know what EBM tells us, but sometimes just choose not to follow it.  For example, if I do a bladder cath on a febrile four-month old without a source, EBM tells us that if no pyuria is present, we should not culture the urine since a positive culture would represent colonization and not infection.  I don’t know about you, but I still send that urine off for culture.  It sure is hard to not give a wheezing four-month old with bronchiolitis at least a trial of nebulized albuterol.        

The third reason we can’t always practice EBM is that we have a clinical question before us, but don’t have any evidence to guide us.  This is particularly true when it comes to choosing between two competing vaccines.  Which rotavirus vaccine works better, Rotateq or Rotarix? Rotateq is a human and bovine recombination with multiple multiple types of human rotavirus antigens from several different strains on the surface of a bovine rotavirus particle.  Rotarix is an attenuated single human rotavirus strain.  Clearly, these are very different products.  Both vaccines showed good efficacy against placebo in various studies done around the world. 

Is one better than the other in preventing disease?  Does one provide longer lasting protection?  Which vaccine provides better protection after a single dose? I would love to have the answer to these questions because I have to pick one.   Answering these questions would require head-to-head testing with tens of thousands of subjects.  My subjective take is that both work well and a big difference between the two probably does not exist.  But “subjective takes” is what the quacks rely upon: “In my experience.”

A bigger question for me is which pertussis vaccine to use.  Sanofi’s products (Pentacel, Daptacel, Adacel) have four pertussis antigens in each dose.  Glaxo’s has only two, but in larger amounts.  Again, the same question:  Does one work better, does one last longer, it one more effective before the entire series is completed?  We have to choose between two Haemophilus influenza vaccines, two quadravalent meningococcal vaccines, two B meningococcal vaccines, two Hep A vaccines, and so on.  Sadly, a lot of us end up choosing based on which company’s reps we like the best or who brings in the best lunches.

One downside to having an answer to these questions is that the company making the lesser of the two approved vaccines might end up folding shop from competitive pressure.  Then we have one vendor for a vaccine, leading to higher prices in the long run.  With a single vendor, if a manufacturing glitch develops, we may run out of vaccine.  Maybe there are some things we are better off not knowing.