The Dr. John Snow Solution circa 1854: The Value of Rapidly Obtained Real-World Evidence Then and Now.

The world in 1854 believed that cholera was caused by “bad air” (miasma) — and moving away from that foul odor would help prevent the disease. From this idea came “best practices” of flush toilet as well as the perceived economic benefit of living in the highlands in urban areas. 

In that year, a London physician, John Snow, had the idea that it wasn’t the air that caused cholera, but rather the source of that odor: Foul water.   

He applied science to the problem. He mapped the cases of cholera he found in 1854 near the Thames river in London. He found a bunch of cases were clustered around a specific water pump on Broad Street. Importantly, he saw few cases around an adjacent area where beer was made.   Thus, Dr. Snow had a naturally occurring test group (those that drank water from the Broad Street pump) and a reference group (beer drinkers from nearby) — today we might call that an intervention group and a comparator, respectively. 

What was the next course of action? (a multiple-choice question).

  1. Forget it, the study was not rigorous enough. Keep quiet: Stick with what was perceived to be the best practice. Don’t make waves.
  2. Announce the results, but clearly state “more research is needed” – it would be premature to do anything based on these very preliminary results.
  3. Contact the Royal Society (or an academic research organization) to seek the equivalent of a $1M grant to study the problem.
  4. Lock the pump and see what happens.

The answer is ‘d’:  Dr Snow had a “eureka” moment (like Archimedes 2000 + years earlier) and then acted based upon his research: He got permission to put a lock on the pump. Cholera cases dropped.  Today you can visit the memory of Dr. John Snow and touch the pump and have a pint of lager in the John Snow pub. (see photo)

What does the John Snow episode of 1854 teach us about today?   

  1. “Best practices” may or may not be based on recently validated scientific studies. It is OK to question authority.
  2. When we have concerns about “best practices” – or a hunch of a better mouse trap – we can certainly conduct rapid research, without engaging the equivalent of the Royal Society.
  3. If the study we conducted is valid and we find the findings are important, rapid action should be encouraged – that is, if the intervention is perceived to “do no harm.”
  4. Continuous scientifically valid monitoring of the consequence of that action (with statistically valid reference groups) should be done to answer the question: Does it work?

Good science followed by action and continuous real-world evidence gathering should be the new paradigm.

For more about Dr. Snow (from my dissertation advisor at UCLA) look here: