How many people REALLY have Ankylosing Spondylitis?

Ankylosing spondylitis, a debilitating inflammatory back condition in which the spine may fuse over time, often shows up in younger people.  (Most arthritis is associated with the aging process.)

This means that people who experience AS, along with complications that may arise from it, do so for longer periods of time than other arthritis sufferers.  But does this raise the death rate in people with AS?

  And if so, exactly what is responsible for the reduction in survival in those with ankylosing spondylitis?

A recent report published in the British Medical Journal entitled "Increased mortality in ankylosing spondylitis is related to disease activity" found that circulatory disease is the most frequent cause of death in persons with AS.  The study also identified other factors that may play a role, including parameters related to the intensity and duration of inflammation.

The authors of the study conclude "these results indicate that, to improve long-term survival in AS, there is a need for early detection and anti-inflammatory treatment as well as a vigilant approach for cardiovascular risk factors."  The authors call for more research on AS.

Measuring AS Prevalence

Estimates vary as to how many people in the US live with AS. A comprehensive epidemiological study on arthritis published in Arthritis & Rheumatism in 2008 found AS prevalence to range from .0003 and .009 in white and east Asian Americans.

(The study authors reported that the data for African Americans suggest AS occurs less frequently for them.)

A recent study published by the American Journal of Medical Science (April 2011) estimated the prevalence of AS to be 0.2% to 0.5% in North America.

The researcher in that study noted several obstacles to determining AS prevalence, namely  genetic testing requirements, the transient nature of AS symptoms and ethnic heterogeneity in the sampled population.

  The good news is the researcher projects these challenges may soon be eased, which may make accurately measuring the presence of AS in populations a more manageable accomplishment.

The Spondylitis Association of America reports that the unique sex- and age-specific onset patterns may provide insight into the way in which AS expresses itself.  The Association says that, clinically, AS occurs about 2-3 times more frequently in males than females, and this ratio increases when the disease is more severe.

AS - A Man's Disease?  Or Does It Equally Affect Both Genders?

Kelly Christal Johnston, an AS advocate who lives with the disease questions the status quo regarding how many people, and what type of people get AS.  "Although AS is believed to be a mans' disease, I believe that in actuality, it may be pretty evenly distributed among the sexes."   Johnston explains that for this and other reasons many cases of AS may go undetected, and that prevalence may be much higher than that which is typically reported in the medical literature.  She echos the  authors' call for more studies.  Research on the topic of ankylosing spondylitis is sorely needed, Johnston tells me.

But Michael Smith, another patient advocate with AS disagrees with Johnston.

  "The facts say that while AS is not exclusively a man's disease, it is still one that primarily affects men.  This is a simple citation of the number of reported cases."

Several others (see the comments below this post) reason that in general women more than men tend to be open to sharing their feelings and talking about their health.  They say that this may explain why, in some situations, it may seem as though there are more women with AS than men.

AS - More Comprehensive Resources

Here are some more comprehensive sources for information about AS:

  • - Note this page was written for medical practitioners, so you may encounter terms you don't understand.



    Gunnstein, B., et. al. Increased mortality in ankylosing spondylitis is related to disease activity. Ann Rheum Dis doi:10.1136/ard.2011.151191.

    Email Interview.  Michael Smith.  Feb 2012.

    Facebook Interview. Johnston, Kelly Christal. Feb 2012.

    Helmick, C. et. al. Estimates of the Prevalence of Arthritis and Other Rheumatic Conditions in the United States. Arthritis & Rheumatism. Jan. 2008.

    Masi, A., Savage, L. Integrated Biomechanical Influences on Ankylosing Spondylitis. Spondylitis Association of America website. April 2009.

    Reveille JD. Epidemiology of spondyloarthritis in North America. Am J Med Sci. 2011 Apr;341(4):284-6.

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