IStockPhoto 5891568 © Jon Schulte

The appendix, a worm-shaped offshoot of the large intestine, is a bit of an anatomical mystery. No one is quite sure what it does, although in 2007 researchers at Duke University Medical Center postulated that the appendix serves as a “safe house” for beneficial bacteria, repopulating the intestine after diseases like dysentery wipe out a good portion of the microbes needed to aid digestion. It’s impossible to predict correctly who will get appendicitis, a life-threatening condition in which the inflamed appendix is usually surgically removed.

The opening from the appendix to the large intestine is quite small, just under half an inch across, and appendicitis may occur when it is blocked. The first sign of appendicitis is generally pain around the navel, which shifts to the lower right abdomen as the appendix swells. Pain usually intensifies over a few hours and may be accompanied by a fever, vomiting, or similar symptoms.

The odds a person will visit a doctor’s office, clinic, or hospital emergency room for appendicitis in a year are 1 in 488.6, while 1 in 985.4 people will be hospitalized for it.

Men contract appendicitis more often than women do. In a year, the odds that a man will be hospitalized for appendicitis are 1 in 881.3. For a woman these odds are 1 in 1,184—a difference of 34%.

Anyone can get appendicitis, but the risks change as we age. The odds a person under 15 will end up in the hospital with appendicitis are 1 in 996.8, but it gets more likely as a person goes through adolescence and into adulthood. The odds for a 15- to 44-year-old are 1 in 806.6. After that the odds decrease, in part because a portion of the population has already been under the knife. For 45- to 64-year-olds, the odds are 1 in 1,219.

Appendicitis can be deadly if the swollen appendix bursts, spewing pus and dangerous bacteria into the interior of the abdomen. This condition, known as a perforated appendix, greatly increases the length of time spent in the hospital and the chances of dying of appendicitis.

The odds that a person will die of appendicitis in a year are 1 in 648,200. You are almost twice as likely to choke to death on your dinner as to die of appendicitis (1 in 343,300).

Although experts can’t tell who will get appendicitis in the first place, studies show that delays in treatment can lead to a higher risk of the appendix bursting. In a 2007 study of 29,637 cases of appendicitis, researchers from Cornell University showed that insurance status was strongly tied to the risk of perforated appendix. After controlling for age, race, gender, and other factors such as socioeconomic status, the researchers found that patients with Medicare were 14% more likely to have a burst appendix than privately insured patients, while uninsured patients were 18% more likely and Medicaid patients were 22% more likely.