Many medical students would not describe themselves as ‘scientists’; there is so much to learn in medical school without the added burden of finding out how it was discovered the first place. Short of taking a year out to do an intercalated research degree, there often is not much exposure to clinical research for students. And yet, every NICE guideline, every audit protocol, every drug in the BNF is the result of decades of diligent research, and we’re expected to know a fair bit about it! So where do we start?!

The research database MEDLINE indexes over 5000 separate journals1, and although research is becoming more focussed on randomised controlled trials2 (the gold standard for research), the sheer volume of literature in existence means nobody could possibly keep up with all of the information out there. But by the time textbooks have crystallised this information, it is often already out of date.

The answer, if you will excuse the research jargon, is meta-analysis! Meta-analysis studies are an analysis of an analysis, and thankfully for us (students, doctors, scientists), specialists in each area go through all of the trials that have been conducted on one specific question (for example, Preoperative medical therapy before surgery for uterine fibroids3) and evaluate how well each trial was conducted, any problems or biases, and come to an answer based on the whole set of available evidence (in this case, GnRHa is of benefit).

To make our lives even easier, these meta-analyses are often gathered together in one place. Perhaps the king of meta-analyses is the legendary Archie Cochrane, founder of the Cochrane Collaboration. This is a worldwide group of over 15,000 people4 split into speciality groups, diligently reviewing evidence and coming up with Cochrane Reviews. The logo of the Cochrane library itself is a forest-plot diagram- a symbol of the systematic review showing how each study favours (or doesn’t favour) the effectiveness of the intervention.

Have a look here...

But it isn’t just the Cochrane Collaboration doing this work. The National Institute for Health and Care Excellence (NICE) use meta-analysis and systematic review to decide which treatments to recommend (including a cost-benefit analysis), and make handy guidelines, potentially based on thousands of clinical trials!

So just like that, most of the high quality medical evidence in the world is distilled down into handy guidelines that are memorable, accessible and make sure patients get the best possible treatments. Now, on to those NICE guidelines…

References

1 - https://www.nlm.nih.gov/bsd/num_titles.html                                                                                       
2 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1250328/
3 - http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD000547.pub2/full   
4 - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2235918/