A few notes of interest:

1) Europe has been doing abx before surgery for a while now. Unfortunately, their data has largely been lacking (thus the need for this trial), creating the impression that this was pushed by their national health services as a cost-saving measure rather than a patient-oriented one. The culture among surgeons in the US, regarding abx for appendicitis, is largely "we don't kill patients just to save a few bucks." The irony that the bucks being saved go directly into their pockets usually goes un-mentioned, but they are in earnest. It's just a win/win that their earnest desire to do the best for patients also pays their bills. It feels nice to get paid for doing the right thing. However, that creates a cultural bulwark against a change in expectations on appendicitis management.

2) There is often a feeling that "if we have to end up doing surgery anyway, we should just do the surgery. There's no value in making the patient go through two such episodes when we have definitive treatment." It's going to be highly subjective whether you think a 1/3 chance of two appendicitis episodes and inevitable surgery vs. a 2/3 chance of avoiding surgery means "it's obvious you should get abx" vs. "it's obvious you should get surgery." I think this study doesn't make anything obvious, but does pave the way to giving patients a reasonable alternative course of action.

3) This is not tantamount to saying "well, we've just been rash all these years in just going straight to appendectomy." Previous trials on this have been, methodologically, poor. Even this trial is a five-year follow-up to what was initially a one-year trial that wasn't adequately persuasive. The initial trial showed a 27% rate of return appendicitis. You can imagine that if the five-year results showed "80%" vs. "36/39%" we'd be having a different discussion. If it showed that having an appendicitis pop up a few years later had more adverse effects, we'd be having a different discussion. So this data was needed, and the fact that docs didn't jump on previously heavily flawed data is... well, docs doing what they're supposed to. You don't want your doc jumping after every poorly-supported shadow.

4) Appendicitis isn't diverticulitis. There's often a layman's shorthand that diverticulitis is just left-sided appendicitis, but it's not. The pathogenesis and appropriate treatments vary quite a bit: conservative treatment of a piece of normal anatomy is quite different from conservative treatment of a piece of herniated, pathologic anatomy. Don't confuse this study for meaning anything regarding the appropriate management of diverticulitis. That's not to say that abx management for diverticulitis is inappropriate, per se, but just saying these are different diseases and not to be confused here.

5) One shouldn't expect this to result in cultural change too quickly. There remains the fact that the primary protection against a malpractice suit is "local standard" - if all the local docs are doing the same thing, it's not malpractice to follow suit. The first doc to go out on a ledge with this is going to be minced meat the moment there's a bad outcome and someone sues. A study is beside the point - if you point to a new study during a suit, the plaintiff's attorney says, "Oh? You have a PhD in study design? No? Then what qualifies you to analyze this study better than every other doctor in your community?" This really won't go anywhere until an entire medical department agrees to go in on this simultaneously - most likely an emergency medicine department. Politically, though, they'd probably have to go to war with their hospital's surgery department to push it through, or otherwise have the surg folk on-side. It'll happen eventually, but it's not going to happen overnight.