Pain-Free Living

Predictors of Ankylosing Spondylitis

By Joseph Gustaitis

A painful condition called ankylosing spondylitis (AS) affects about 32 out of every 100,000 people in North America. The term itself is a mouthful, but it becomes clearer when you break it down. It combines the Greek words for “crooked” (ankylose) and “vertebra” (spondylos) with the suffix “-itis,” which means inflammation. In other words, it means inflammation of a crooked spine, which explains why the main symptom of AS is back pain. According to the National Institutes of Health, although AS affects mostly the spine, in some people it can affect the shoulders, ribs, hips, knees and feet. It’s a chronic form of arthritis that affects about twice as many men as women, and it almost always begins early—in the teenage or young adult years. In some people, the pain is intermittent; in others, it’s continual. The cause is unknown, but researchers believe there is a genetic component.

Recently, a study presented at a European congress on rheumatism discovered some fascinating evidence about how AS might be predicted based on certain components of a person’s background. The researchers examined data on 1,587 patients with AS and 6,706 people without the disease that were collected from several Swedish national registers. After crunching the numbers, they identified three factors in the development of AS: low birth weight, having older siblings and hospitalization for infection.

Low birth weight was defined as less than 6.6 pounds (3,000 grams). That low birth weight was a factor in AS was not unexpected—previous research has shown low birth weight can predict the development of diabetes and rheumatoid arthritis. Similarly, scientists previously had found a link between having older siblings and the development of asthma; and it’s also known that infections can trigger what’s known as reactive arthritis, which results from exposure to a certain type of bacteria.

The importance of the new research is that it sheds valuable new light on the nature of AS. One of the researchers said the study will help scientists get closer to discovering the underlying cause of AS. As with other diseases, knowing the cause often is the first step in discovering a cure.

Last Reviewed 12/7/15

Joseph Gustaitis is a freelance writer and editor based in the Chicago area.

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