A curious trend in appendectomies by residents

Some experts are worried that laparoscopic cholecystectomy is so prevalent that future surgeons may have difficulty doing open cases. I was going to blog about the possibility that open appendectomy would become the next operation that next generation surgeon might have trouble with. But while looking at some data [link added 12/4/15] collected by the RRC for Surgery, I was struck by something else.

Since 1999, the total number of appendectomies (open and laparoscopic) performed by surgical residents who completed 5 years of training has risen by 65.1% compared to the total number of appendectomies done in the US, which has increased only 16.4%. Here are the numbers:

Except for the academic year ending in 2006, the average total appendectomy rate per resident has risen every year since 2000. The chart below displays that change and the changes in the numbers of open and laparoscopic appendectomies.

Click on chart to enlarge

The difference in the average combined number of appendectomies between the two academic years ending 2000 and 2014 is significant, p < 0.0001.

The population of the US rose from 279 million in 1999 to 318.9 million in 2014, an increase of 14.3%. The number of appendectomies done in the US for those years was about 281,000 vs. about 327,000 respectively, a 16.4% increase. The appendectomy rate increase does not significantly differ from the increase in population.

The difference between the total number of appendectomies done in the US and the total done by residents at teaching hospitals was significant, p < 0.0001.

What is going on here? Why is the increase in the rate of appendectomies being done by residents significantly higher than the rise in the rate of appendectomy for the entire country?

I posed this question on Twitter and got a number of replies.

Could the difference be due to more appendectomies being referred to teaching hospitals? It is possible, but except for a few anecdotes, a pattern of has not emerged. For example, the change in total numbers of cholecystectomies has been much more modest. In 1999-2000, graduating residents did 99.5 cholecystectomies and in 2013-14, they did 120.9, an increase of only 21.5% which is significantly lower than the increase in appendectomies, p < 0.0001.

Have academic centers increased their catchment areas? I dont think catchment areas have changed much in 15 years.

Are attending surgeons lazier than they were in 1999-2000? Thats not likely. For most cases, they had to be present in the OR anyway in both eras.

Are surgeons doing more appendectomies to increase their incomes? If that were so, the number of normal appendices (that is, appendices that were judged to be not inflamed by pathologists) would be higher than it was in 99-00. In fact, the reverse is true. The rate of normals has fallen drastically over the years.

Residents might not have logged all their appendectomies in the past or maybe they are inflating their numbers now. Those are interesting theories both of which cannot be proven.

Could it be because of increased use of CT scans? In a recent New England Journal paper, Dr. David Flum suggests the CT scan that just about every patient with right lower abdominal pain now gets may be too sensitive. This could lead to the overdiagnosis of mild cases of appendicitis that might have resolved without any intervention.

However if the issues is CT scan overdiagnosis, the rate of appendectomy nationwide would be as high as the rate in teaching hospitals.

Im out of ideas. Can you explain the appendectomy mystery?

By the way—in case you missed it in the table above—over the 15-year period, open appendectomies have decreased 68% and laparoscopic appendectomies have increased 546%.

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