In many countries around the world, people use World Ankylosing Spondylitis (AS) Day as an occasion to raise awareness of the condition.

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Ankylosing spondylitis (AS) is a form of inflammatory arthritis that primarily targets the back and pelvic joints. More than 3 million people in the United States live with AS.

World AS Day usually occurs on the first Saturday of May, but it moves to the second Saturday if the first one falls on May 1. In 2021, World AS Day will take place on May 8.

According to the Axial Spondyloarthritis International Federation, World AS Day aims to:

  • raise awareness of the condition
  • help people connect to support and care
  • share information about AS

In an effort to help coincide with the resources and support around World AS Day, the Spondylitis Association of America (SAA) changed Ankylosing Spondylitis Awareness Month to May in 2019.

In honor of World AS Day, we have listed 10 scientifically backed facts about AS below.

The SAA notes that there are two classification systems for spondyloarthritis or spondylitis: traditional and newer.

The traditional classification system includes six diseases, while the newer one has two broad categories that cover the different diseases.


The traditional breakdown includes:

  • ankylosing spondylitis
  • undifferentiated spondyloarthritis
  • enteropathic arthritis
  • reactive arthritis
  • psoriatic arthritis
  • juvenile spondyloarthritis


The newer system includes:

Axial spondyloarthritis (AxSpA)

AxSpA causes inflammation in the spine or pelvis and includes AS. It may also include enteropathic arthritis, undifferentiated spondyloarthritis, psoriatic arthritis, and reactive arthritis.

Peripheral spondyloarthritis (pSpA)

This type typically causes pain or swelling in joints outside the spine. It primarily refers to psoriatic arthritis but may include undifferentiated arthritis, reactive arthritis, and enteropathic arthritis.

People living with AS can experience different symptoms. For some, AS will cause mild back pain and stiffness that comes and goes. Others may experience more severe, constant back pain.

According to the National Institutes of Health (NIH), a person may also experience the following symptoms:

  • inflammation, stiffness, or pain in other joints
  • skin rashes
  • loose bowel movements
  • weight loss or loss of appetite
  • trouble taking a deep breath
  • changes in vision or pain in the eye
  • fatigue
  • stomach pain

The Arthritis Foundation also points out that AS may affect a person’s:

  • lungs
  • digestive tract
  • eyes
  • heart

Researchers still do not know the exact cause of AS.

The SAA states that a person’s genes likely play a role in the development of AS. It points out that more than 95% of Caucasian people living with AS have the protein marker HLA-B27.

However, a person without this marker can still have AS, as there are about 60 different genes that play a role in the development of AS.

The SAA also says that a triggering event, such as a bacterial infection, is likely necessary for AS to occur. The thought is that bacteria may get into the bloodstream and trigger the immune system, which can cause AS to develop.

There are several potential risk factors for developing AS. Having one or more of the risk factors does not necessarily mean that someone will develop AS, but identifying them may help a person get an earlier diagnosis.

The Global Healthy Living Foundation notes that risk factors for AS include:

  • genetic factors linked to AS, such as HLA-B27
  • family history of AS
  • uveitis, a form of eye inflammation
  • living with inflammatory bowel disease
  • environmental exposure to pollutants, infection, or toxins

According to a 2016 study in Medicine, AS tends to affect males and females differently.

Compared with females, males typically:

  • develop the disease at a younger age
  • have lower disease activity but worse disease progression
  • have worse spine mobility
  • have a better quality of life

Compared with males, females are more likely to:

  • get a diagnosis without delay
  • develop symptoms in their arms and legs
  • develop swelling, inflammation, and pain, causing a lower quality of life

People living with AS may be interested in trying different therapies that do not involve medication to treat their symptoms.

According to the SAA, additional therapies that a person may find beneficial include:

  • chiropractic care
  • massage therapy
  • aquatic-based therapies
  • physical therapy
  • complementary and alternative medicine (CAM)
  • exercise
  • transcutaneous electrical nerve stimulation (TENS)

Acupuncture may be effective for some people with AS. A 2020 review of 10 studies found that the evidence supporting its use is promising. However, the authors concluded that more structured research is necessary to confirm its benefits.

Before starting any new therapies, a person should talk with their doctor. The doctor will recommend how to proceed and advise against certain methods that may have side effects.

According to the Arthritis Foundation, a person with AS should ensure that they are taking care of themselves holistically.

Self-care can help a person feel better. Some self-care tips for people living with AS include:

  • quitting smoking, if a smoker, or avoiding secondhand smoke
  • taking breaks on more challenging days
  • incorporating lots of stretching, especially when the body is warm, such as after a bath or shower
  • eating a diet rich in nutrients from fruits, vegetables, whole grains, healthy fats, and lean proteins
  • practicing good posture

The NIH explains that no single test can confirm an AS diagnosis. Instead, if a doctor suspects that a person has AS, they will make a diagnosis by:

  • discussing the person’s family history
  • asking about their symptoms and medical history
  • performing a physical examination
  • ordering X-rays or other imaging tests

There is currently no cure for AS, although research in this area is ongoing.

Treatment for AS focuses on:

  • keeping the spine straight
  • reducing pain and stiffness in the back and other joints
  • avoiding or minimizing organ and joint damage
  • preserving mobility and function
  • improving quality of life

Researchers are investigating the underlying mechanisms of AS and trying to determine whether there are more effective treatment options.

It is likely that additional research will help the scientific and medical community better understand AS and provide even more effective care for people in the future.

For example, an upcoming trial is looking at the role of gut microorganisms and how they may affect AS disease activity.

A person can ask their doctor about the possibility of signing up for a clinical trial. They can also look at available clinical trials on the U.S. government’s clinical trials website or the SAA website.

AS affects a large number of people in the U.S. and across the world. World AS Day helps raise awareness of AS to help people better manage and cope when they or a loved one receives a diagnosis of AS.