A close relative of mine had a bit of a scare this week when she ended up admitted to the hospital for (what was ultimately diagnosed as) acute appendicitis. She ended up in surgery with a partially ruptured appendix, though she’s doing fine now.

When I mentioned this saga to a coworker, she said she felt like she didn’t hear much about appendicitis anymore. We started wondering what the rates were, and if they were going down over time. Of course this meant I had to take a look, so here’s what I found:

1. The rates have fallen over the decades, and no one is really sure why. This paper suggests that rates fell by 15% between 1970 and the mid 80s, but no one’s sure what happened. Did appendicitis become less common? Less deadly? Or did our diagnostic tools get better and some number of cases get reclassified? This is a valid question because of this next point….
2. A surprisingly high number of appendectomies aren’t necessary. An interesting study from 2011 showed that about 12% of patients who get an appendectomy end up not getting diagnoses with appendicitis. They suggest that this rate has been falling over time which could have helped the numbers in point #1. Is it the whole story? It’s not clear! But definitely something to keep in mind.
3. The number of incorrectly removed appendixes may not be going down. Contrary to the assertions of the study above, it’s not certain that misdiagnosed appendicitis is going down. Despite better diagnostics, it appears that easier surgical techniques (i.e. laparoscopic surgeries) actually may have increased the rate of unnecessary surgeries. This sort of makes sense. If you have to do a big complicated surgery, you are going to really want to verify that it’s necessary before you go in. As the surgery get easier, you make focus more on getting people to surgery more quickly.
4. The data sources may not be great. One of the more interesting papers I found compared the administrative database (based off insurance coding) vs a pathology database and found that insurance coding consistently underestimated the number of cases of appendicitis. Since most studies have been done off of insurance code databases, it’s not clear how this has skewed our view of appendicitis rates.
5. Other countries seem to be seeing a drop too Whatevers going on with appendicitis diagnosis, the whole world seems to be seeing a similar trend. Greece has seen a 75% decrease. England has also seen falling rates. To be fair though, some data shows it’s mixed. Developed countries  seem to be stabilizing, newly developed countries seem to see high rates.

So who knew how hard it was to get a handle on appendicitis rates? I certainly thought it would be a little more straightforward. Always fascinating to explore the limits of data.