Ankylosing spondylitis (AS) is relatively rare. Older data estimate that 0.1 to 1.4% of the global population have AS. The condition is more common in people with a gene known as HLA-B27.
The statistic above comes from a 2014 study.
AS is a type of chronic inflammatory arthritis. Early in the disease course, it causes low back pain and stiffness. Over time, it can cause fusion of the spinal vertebrae and significant mobility issues.
Continue reading to learn more about the prevalence of AS and who it affects.
A note about sex and gender
Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.
Older data suggests that AS affects around 0.1 to 1.4% of the global population. In North America, AS affects around 31.9 people for every 10,000.
However, as this information is old and awareness of AS has increased over time, these figures may not be accurate, and the number of people with AS may be higher.
AS can affect anyone, but it is more common among certain groups. It has a strong genetic basis, for example. Experts have identified several genes that affect a person’s risk.
The strongest link is with the human leukocyte antigen (HLA)-B27 gene. Usually, HLA genes support the immune system and help it identify foreign viruses and bacteria.
The prevalence of HLA-B27 varies among different ethnicities, affecting:
- 7.5% of non-Hispanic white people
- 4.6% of Mexican-American people
- 1.1% of non-Hispanic Black people
Individuals with a family history of AS are also more likely to have the HLA-B27 gene. However, people can develop AS without being positive for HLA-B27, and the strength of the connection between genetics and AS is not the same across ethnic groups.
For example, a
Overall, further research is required to understand the link between AS, genetics, and the social or environmental factors that may influence its onset and progression.
Historically, experts believed that AS affected more males than females. However, a
The condition also affects males and females differently. Females experience a higher frequency of other conditions associated with AS. These include enthesitis, psoriasis, and inflammatory bowel disease (IBD). Females also have significantly lower response rates to medications and report a lower quality of life.
In contrast, acute anterior uveitis is more prevalent in male individuals. This condition affects the eye and can cause pain and vision problems.
The differences in presentation and the rate of additional conditions between males and females may be due to differences in biology and medical treatment. For example, females experience
In addition to differences in AS between races, ethnicities, and sexes, there are also geographic differences. Experts are unsure why this is the case, but genetic, environmental, and lifestyle factors specific to each country could play a role.
The table below shows how many people have AS, on average, per 10,000 citizens in various countries. This data comes from an older 2014 review:
|Prevalence per 10,000 people
However, it is worth noting that these figures are estimates that may not translate to current populations, given increased geographic mobility and diagnosis.
Further research is needed to understand the link between genetics and AS fully.
AS is a serious disease for some people. AS typically begins with back pain and stiffness, which can remain stable for some time. But in one study, researchers found that
More advanced AS can cause the spine to fuse and limit movement and physical activity. In some cases, AS can damage other organs in the body and cause complications.
AS has some effect on a person’s mortality, but this lessens with earlier diagnosis and effective treatment. However, it can co-occur with various other conditions that may be life threatening, such as cardiovascular disease, heart attacks, and stroke.
Therefore, it is important to talk with a doctor about any concerning symptoms. Early diagnosis and treatment are essential to managing AS and preventing serious complications.
AS is an uncommon form of chronic inflammatory arthritis that affects the spine and other joints. In a 2014 study, around 0.1 to 1.4% of people globally had AS.
The prevalence of AS varies by age group, sex, race or ethnicity, and location and affects males and females differently. It is also more common in those who are positive for the HLA-B27 gene.