Appendix removal associated with development of Parkinson’s disease

Patients who had their appendix removed were more likely to develop Parkinson’s disease than those whose appendix remained in place, according to the largest study to address the relationship between the two conditions. The retrospective study involving more than 62 million patient records from 26 health systems will be presented at Digestive Disease Week® (DDW) 2019.

“Recent research into the cause of Parkinson’s has centered around alpha synuclein, a protein found in the gastrointestinal tract early in the onset of Parkinson’s,” said Mohammed Z. Sheriff, MD, lead author of the study and a physician at Case Western Reserve University and University Hospitals Cleveland Medical Center, Ohio. “This is why scientists around the world have been looking into the gastrointestinal tract, including the appendix, for evidence about the development of Parkinson’s.”

Previous findings on appendectomies and Parkinson’s have been inconsistent, with some studies showing no relationship and a recent study from Europe showing patients who still had their appendix were more likely to develop Parkinson’s. This contradiction prompted Dr. Sheriff and colleagues to seek answers to the question using U.S. data from an Ohio-based electronic health records company that draws data from 26 major integrated health systems.

Researchers analyzed electronic health records representing more than 62.2 million patients and identified those who had appendectomies and were diagnosed with Parkinson’s disease at least six months later.

They found that among 488,190 patients who had undergone appendectomies, 4,470, or .92 percent, went on to develop Parkinson’s. Of the remaining 61.7 million patients without appendectomies, they identified only 177,230, or .29 percent, who developed the disease. According to this analysis, patients who had an appendectomy were more than three times as likely to develop Parkinson’s than those who had not.

Researchers found similar risk levels across all age groups, regardless of gender or race. Other than the six-month washout period programmed into their initial query of the database, researchers could not tell from the de-identified records exactly how much time passed after the appendectomy until Parkinson’s was diagnosed.

“This research shows a clear relationship between the appendix, or appendix removal, and Parkinson’s disease, but it is only an association,” Dr. Sheriff said. “Additional research is needed to confirm this connection and to better understand the mechanisms involved.”