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Epidemiology of Ankylosing Spondylitis

Studies of various populations have revealed intriguing data relative to geographic distribution, race, ethnicity, and age of onset with respect to ankylosing spondylitis (AS). As of 2003, Newman, et al., reported that AS may affect up to 1 million adults in the United States.¹¹⁴²⁰  AS has traditionally been associated with higher rates in males, but often as a result of misdiagnosis with females.¹¹⁴⁵³  The male-to-female prevalence rate may be as high as 3:1.¹¹⁵⁰⁰  Males are most often affected in the spine and pelvis, with females being more affected by symptoms occurring in the knees, wrists, hips, and pelvis.¹¹⁴⁵² 

The prevalence of AS has been mostly studied in white populations and may vary depending on geographic regions (0.2% white Americans; 0.9% white Germans; 1.4% Norwegian populations) as the disease appears closely linked to the human leukocyte antigen (HLA)-B27 antigen as well as other, less well-defined environmental factors. Certain populations such as African and Japanese seem to have low expression of the disease consistent with their low frequency of the HLA-B27 polymorphism. Higher prevalence rates of the genetic polymorphism occur in certain Native American tribes, Inuits, and Siberian Chukotkas. The incidence and prevalence may not only vary between major geographic regions, but also may vary within regions depending on the genetic make up of the population.¹¹⁴⁵³ 

Symptoms associated with AS typically begin when the individual is young, and are most commonly diagnosed in the second and third decades of life. The peak age of onset is near the third decade of life (mean age around 28 years) with a second, smaller peak around the fifth decade of life.^{11453,  11452}  The onset of childhood AS appears to be more prevalent in developing countries (40%) compared to America and Europe (15%).¹¹⁴⁵³ 

Content on this page was last reviewed on January 01, 2010.

Content on this page was last changed on March 27, 2009.