Obesity Worsens Outcomes for Ankylosing Spondylitis


For many years, researchers linked obesity to a number of other health conditions. Now, Taiwanese researchers identify a new cause for concern: worsening health outcomes for patients with ankylosing spondylitis (AS). According to Ankylosing Spondylitis News, obesity represents a risk factor for heightened disease activity, more inflammation, and worse cardiovascular outcomes. Check out the full findings published in the International Journal of Rheumatic Diseases.


According to the Mayo Clinic, obesity is not just a cosmetic issue involving excess fat. Rather:

It is a medical problem that increases your risk of other diseases and health problems, such as heart disease, diabetes, high blood pressure, and certain cancers. There are many reasons why some people have difficulty avoiding obesity; [it usually] results from a combination of inherited factors, combined with the environment and personal diet and exercise choices.

Obesity is measured by body mass index (BMI). You are considered obese if your BMI is 30 or higher. There are complications associated with being obese, including:

  • High blood pressure
  • Abnormal cholesterol levels
  • Heightened risk of heart disease, stroke, and gallbladder disease
  • Poor liver function
  • Type 2 diabetes
  • Sleep apnea
  • Infertility
  • Menstrual irregularities
  • Heartburn
  • Osteoarthritis
  • Depression

The Research

Prior to this study, there was little research on the association between obesity and ankylosing spondylitis. Researchers used BMI, waist circumference, and waist-to-height (WHtR) ratio as measurements. While a BMI greater than 30 is usually associated with obesity, researchers in this study used a BMI of 27+, waist circumference of 31.4 inches (female) or 35.4 inches (male), or a WHtR of 0.5+.

Altogether, 105 patients with AS enrolled in the study. The median age was 48. 92 patients (87.6%) were male; 13 patients (12.4%) were female. Of these patients, 29 (27.6%) were obese. 36 (34.3%) were overweight. The remainder were considered normal weight.

However, when taking into account waist circumference and WHtR, around 67-77 patients were considered centrally obese. 10.5% of patients had diabetes, and 18.1% had high blood pressure.

Through testing, researchers discovered that obese patients experienced less mobility, more spinal damage, more progressive disease activities, higher inflammation markers, and worse liver function. Additionally, obesity increased the risk of high blood pressure.

Ankylosing Spondylitis (AS)

While there are many causes of ankylosing spondylitis, researchers are still unaware of exactly what these causes are. Genetics and environmental factors are thought to play a role. In fact, while HLA-B, IL1A, ERAP1, and IL23R gene mutations are linked to AS, not all people with these mutations develop the condition. AS is part of a group of diseases called spondyloarthropathies. The condition causes chronic spinal inflammation. However, this inflammation may spread to the shoulders, hips, or even knees. Symptoms include joint pain and inflammation, reduced flexibility, fatigue, and tendon inflammation. Additionally, around 40% of patients with AS experience uveitis (eye inflammation), vision loss, eye pain, and sensitivity to light. Learn more about AS here.

Jessica Lynn

Jessica Lynn

Jessica Lynn has an educational background in writing and marketing. She firmly believes in the power of writing in amplifying voices, and looks forward to doing so for the rare disease community.

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