This was asked at a writing workshop that I led recently. How do you go about comparing two guidelines?
Comparing is related to, but not the same as, critically appraising a guideline, in which you are looking at guidelines individually. Trisha Greenhalgh's very useful book How to read a paper has a chapter about appraising guidelines, with ten questions to ask about a clinical guideline. There is also a systematic review of appraisal tools in this article in PLoS One by Ulrich Siering and colleagues.
The National Guidelines Clearinghouse has a "Compare" tool. You choose the guidelines you want to compare, by ticking a box in the search results list. Then you choose which sections you want to compare, and you can then see on screen or in a spreadsheet, those sections side by side. It takes the sections as they are, which means that you may be comparing very differently arranged texts.
A PubMed search for comparison clinical guidelines finds some papers that compare guidelines for specific conditions. It also finds many papers about comparing other things, not comparing actual guidelines. The search worked much better once I had corrected comparision to comparison although the wrong spelling still found a handful of things!
Missing out the word clinical, so comparison guidelines, finds more (and more irrelevant things too, of course).
Searching more specifically, for example comparison guidelines valvular heart disease, would of course be a way forward.
A quick look at MeSH headings for something old enough to have them suggests:
Practice Guidelines as Topic/
Searching those headings (type in practice guidelines as topic comparative study) together finds a lot of relevant looking papers that I had not seen before, (as they did not use the word "comparison"), amongst other papers comparing decisions or results related to recommendations in guidelines. Combine this search with a clinical area or subject.
Comparing is related to reporting guidelines too. The AGREE Instrument helps assess the methodology of a guideline. This is in the Equator Network Library along with the RIGHT Statement for reporting practice guidelines and some other things.