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What Triggers Ankylosing Spondylitis (AS)?

What is ankylosing spondylitis?

Ankylosing SpondylitisThe exact cause of ankylosing spondylitis is not known. A combination of age, sex, and genetic and environmental factors may increase the risk of ankylosing spondylitis.

Ankylosing spondylitis (AS), also called Bechterew disease, is a chronic inflammatory disease. Ankylosing spondylitis affects the joints of the body, especially the small joints of the spine and the pelvic (hip) bone. It can also affect multiple organ systems in rare conditions. Prolonged inflammation of the joints eventually leads to the fusion of the joints leading to deformities.

What triggers ankylosing spondylitis?

The exact cause of ankylosing spondylitis is not known. A combination of age, sex, and genetic and environmental factors may increase the risk of ankylosing spondylitis. 

Genetic factors: There is a strong association of AS with HLA-B27 and HLA-B60 genes. Other genetic abnormalities associated with AS are not as common as HLA-B27. HLA (human leukocyte antigen) is a type of protein present on the surface of white blood cells that protect the body from infections.  AS is more common in people with a family history of the disease. In the case of identical twins, there is a 60 percent increased risk in the other twin.

Ethnicity: AS is more common in people of Caucasian descent. 

Environmental factors: AS usually occurs due to genetics and environmental triggers together. The exact environmental triggers are not known but based on research, some possible triggers are:

  • Infections
  • Toxins 
  • Pollution 
  • Smoking 
  • Changes in the normal gut organisms 

Age: AS is commonly seen in a younger age group of 20 years to 40 years. Rarely, younger individuals are affected by AS (10 to 20 percent). It is called juvenile ankylosing spondylitis and symptoms occur before the age of 16 years.  

Sex: AS is found to be three times more common in men than women.

Is ankylosing spondylitis an autoimmune disease?

Ankylosing spondylitis is considered as an autoimmune disease. Autoimmunity of ankylosing spondylitis is linked to defects in the HLA-B27 gene, seen in people suffering from the disease. However, AS does not develop in everyone who is HLA-B27 positive.

  • Individuals with the expression of HLA-B27 in their cells have higher chances of the immune system attacking the body’s own cells. 
  • Defects in another protein, HLA-B60, further increases the risk of developing AS along with HLA-B27.
  • Presence of other autoimmune diseases like psoriasis and inflammatory bowel disease (IBD) can trigger AS.

What are the complications of ankylosing spondylitis?

Long-term disease with prolonged joint inflammation leads to chronic pain, joint deformities, and limited range of motion. This is due to the destruction of the joints and joint fusion. 

The most common deformity is seen in the spine. Chronic inflammation of the spine leads to a “hunchback” deformity. The spine can also fracture and cause compression of the spinal cord, which can lead to paralysis

AS can also affect other organ systems, causing inflammation and damage, which may sometimes be irreversible and lead to failure of multiple organs. All of these complications can be reduced through proper treatment and lifestyle modifications.

How is ankylosing spondylitis treated?

There is no cure for AS. With appropriate medical and surgical treatment, and lifestyle modifications, the disease progression can be delayed. Complications can be prevented and patients can achieve symptomatic relief with these changes and treatments. The physician will prescribe a treatment plan based on the extent of the disease and patient history.


  • NSAIDs (non-steroidal anti-inflammatory drugs), e.g., ibuprofen, can be given orally to reduce pain and inflammation. 
  • Sulfasalazine: These drugs can be given to patients who do not respond to NSAIDs, are allergic to NSAIDs, or have irritable bowel disease. Sulfasalazine also reduced spinal stiffness and inflammation of other joints.
  • Medication that modifies and/or suppresses the immune system: These drugs are tumor necrosis factor (TNF) inhibitors, interleukin inhibitors, corticosteroids, and more. They reduce inflammation, pain, stiffness, delay the disease progression, and reduce or prevent complications. 


  • Severely damaged joints with deformity may need surgery. Joint replacement surgery can be performed on the knees and hips.
  • Surgery to realign the spine, called an osteotomy, may also be done. 

Lifestyle modifications

  • Physical therapy and posture training. 
  • Healthy diet, exercise, and maintaining a normal body weight.
  • Alternate methods for symptomatic relief:
    • Using heating pads and/or ice packs, massage therapy, etc. can reduce pain and stiffness.
    • Counseling can provide emotional support, and prevent or treat depression associated with chronic diseases.
  • Avoiding environmental triggers such as smoking, exposure to harmful chemical toxins, fumes, and pollutants.



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