GRADEing Studies & Evidence

July 19th, 2012 by Will Humble Leave a reply »

As I mentioned in my previous post, scientific studies (e.g. experimental v. observational design) have different strengths and weaknesses. Sources of evidence range from case reports at the lower end to well-designed large randomized experimental clinical studies that minimize bias.  Relying on poor quality evidence can lead to policy decisions that aren’t in patients’ best interests- and it’s super important to figure out the actual “weight of evidence” that published studies provide- so public health can make good evidence-based decisions. 

That’s where the Grading of Recommendations Assessment, Development and Evaluation- or GRADE system comes in.  The GRADE system was developed to provide researchers and policy makers a systematic way of grading the strength of studies to help policy makers in medicine and public health to interpret studies and make better decisions.  The GRADE system has all kinds of applications.  For example, the U of A used the GRADE methodology to evaluate the quality of the studies looking at the benefits and harms of using Cannabis to treat the conditions that were petitioned to add to the list of qualifying conditions for a medical marijuana card.

You can read alot more about the GRADE system and how it works in this article in the British Medical Journal (unfortunately you need to pay to read the whole thing).



  1. Chris says:

    I was curious if you had considered the research being done by CMCR at the University of California. They don’t seem to have any direct studies on the conditions being considered, but I would assume they would be a more valuable resource for current information than the UofA. A link to their website is below.

  2. nancy d. says:

    In regards to research, what research was done by the pharmaceutical companies for Marinol, the THC pill? What’s the difference between smoking a controlled substance and ingesting a multi-billion dollar company’s pill? I think I just answered my own question….

    • Will Humble says:

      Nancy D
      Before voters passed the AMMA, I was on the record talking about the importance of scientific research for medication. As a matter of fact, I blogged about THC already being available in a synthetic form – – this form of THC has gone through thorough scientific studies. Scientific studies that track the impact – whether it is good or bad – of a substance on a condition.

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