Ankylosing spondylitis affects roughly 0.5 percent of American adults — about one person in 200. US population data put it at 0.52 to 0.55 percent. The wider published range is 0.2 to 0.5 percent, depending on how cases are counted. It belongs to a larger disease family, axial spondyloarthritis. That family affects 1.0 to 1.4 percent of adults — closer to one person in 80.
According to PubMed, those figures come from the National Health and Nutrition Examination Survey. It is the same national survey used to track blood pressure and diabetes in the United States (Reveille JD, Weisman MH. The epidemiology of back pain, axial spondyloarthritis and HLA-B27 in the United States. Am J Med Sci. 2013;345(6):431-6. DOI; and Reveille JD. Epidemiology of spondyloarthritis in North America. Am J Med Sci. 2011;341(4):284-6. DOI).
Not in the way most people mean by “rare.” A condition that affects one adult in 200 is not a medical oddity. For comparison, the same national survey put chronic back pain in US adults at 19.4 percent. About a third of that is inflammatory. The disease hides inside a very large and very ordinary-looking group.
What is truly uncommon is being diagnosed with it promptly. That is a different problem. It is the one that actually harms patients.
According to PubMed, a review and pooled analysis of 64 studies looked at axial spondyloarthritis. The average delay from first symptoms to diagnosis was 6.7 years (95% CI 6.2 to 7.2). In psoriatic arthritis, the delay was 2.6 years. Same specialty, same clinics, less than half the wait. And the delay had not improved over time when the studies were sorted by year (Zhao SS, et al. Rheumatology (Oxford). 2021;60(4):1620-1628. DOI).
The delay is not shared equally. According to PubMed, a 2024 review and pooled analysis found the delay averaged 1.48 years longer in women than in men (95% CI 0.83 to 2.14). The rules used to identify the disease were first studied mostly in men (Bandinelli F, et al. J Pers Med. 2024;14(1):91. DOI).
So the accurate answer to “is it rare” is this: the disease is not rare, the diagnosis is late, and the delay is longer if you are a woman. Picture a patient in their forties who was told at 25 that they had ordinary mechanical back pain. That is not an unusual case. It is the typical case.
Because the first complaint — back pain in a young adult — is one of the most common in medicine. And almost none of it is inflammatory.
According to PubMed, chronic back pain in US adults runs around 19.4 percent. Nearly a third of that meets criteria for inflammatory back pain (Reveille and Weisman 2013, DOI). An earlier NHANES analysis put inflammatory back pain at 0.8 percent of adults aged 25 to 49 overall. It was 6.7 percent among those who had a back pain episode lasting two weeks or more (Dillon CF, Hirsch R. Am J Med Sci. 2011;341(4):281-3. DOI).
The signal is there. But it is buried in a lot of noise. You can only find it if someone asks the specific questions that sort inflammatory back pain from mechanical back pain.
Read this part closely. The pattern is nearly the reverse of ordinary mechanical back pain.
Beyond the spine, some features raise the odds a lot. These include a red, painful eye that keeps coming back (acute anterior uveitis), psoriasis, and inflammatory bowel disease. So do heel pain where the Achilles tendon attaches or under the heel, a swollen finger or toe, and a family history of any of these. Fatigue out of proportion to the pain is common. It is a real feature of the disease, not a personality trait.
HLA-B27 is a genetic marker closely tied to ankylosing spondylitis. It causes a lot of confusion in both directions.
According to PubMed, about 6.1 percent of people in the United States carry HLA-B27, after adjusting for age (95% CI 4.6 to 8.2). That is roughly one American in 16. By group, it was 7.5 percent in non-Hispanic whites and 4.6 percent in Mexican Americans. It was 3.5 percent across all other US racial and ethnic groups combined (Reveille JD, Hirsch R, Dillon CF, Carroll MD, Weisman MH. Arthritis Rheum. 2012;64(5):1407-11. DOI).
Now set that against a disease rate of about 0.5 percent. The math is harsh in both directions. The overwhelming majority of people who carry HLA-B27 will never develop ankylosing spondylitis. A positive test in someone without the symptom pattern means very little. And a negative test does not rule out the disease. A real minority of patients with axial spondyloarthritis are B27-negative. This is one reason the diagnosis is missed more often in women.
The test is one input into a diagnosis made by a rheumatologist. The rheumatologist combines history, exam, inflammation markers, and imaging of the sacroiliac joints. It is not a screening test for back pain, and it should not be ordered as one.
Diagnosis and disease-modifying treatment belong with rheumatology. We want to say that plainly, not blur it. Ankylosing spondylitis is an immune disease. Some medicines change its course. These include anti-inflammatories at full doses, and biologic drugs that target TNF or IL-17. Rheumatologists prescribe and monitor them. Does your history match the pattern above? Have you never seen one? Then that referral is the most useful thing that can happen for you. We will help make it happen.
Where an interventional pain practice does have a role:
Surgery is not part of the treatment plan for ankylosing spondylitis itself. The disease is driven by immune inflammation and new bone growth. No operation changes that process. No procedure treats the underlying condition.
There are two situations in a patient with AS where surgery is the right talk. Neither is a treatment for the disease:
Dr. Gurpreet Singh Padda, MD, MBA, MHP is a licensed physician and surgeon with surgical privileges. This practice performs minimally invasive spine procedures. For ankylosing spondylitis, three things help. Early rheumatology care. Steady exercise. And treating the mechanical pain sources that build up alongside the disease. It is not an operation aimed at the disease.
Some back pain started before 45, is worse after rest, better with movement, and wakes you in the second half of the night. That is a specific pattern with a specific meaning. It deserves to be named, not managed forever. We see patients from across St. Louis, Clayton, St. Charles and the Illinois Metro East. Call us or request an evaluation.
More on this condition from Dr. Padda on YouTube:
About 0.5 percent of US adults, or one person in roughly 200, based on national survey data. Published estimates run from 0.2 to 0.55 percent, depending on how cases are defined. The wider disease family, axial spondyloarthritis, affects 1.0 to 1.4 percent, closer to one person in 80. Those are figures for adults today, not lifetime risk. Read more: The scale of autoimmune disease.
Not by the usual meaning of rare. Around one adult in 200 has it. It sits inside a population where chronic back pain runs at 19.4 percent. That is exactly why it hides. What is truly unusual is a prompt diagnosis. The average delay from first symptoms to diagnosis is 6.7 years, and it is longer in women. Read more: When autoimmunity is the source of pain.
Because the first symptom is back pain in a young adult. That is extremely common and almost never inflammatory. Telling the two apart takes specific questions that are not routinely asked. How old were you when it started? Does rest make it worse? Does morning stiffness last beyond 30 minutes? Does it wake you in the second half of the night? The average delay is 6.7 years, and it has not improved over time. Read more: When the scan does not match the pain.
Probably not. About 6.1 percent of Americans carry HLA-B27, while ankylosing spondylitis affects about 0.5 percent. So the vast majority of carriers never develop it. The marker raises the odds in someone whose history already fits. It does not make a diagnosis on its own. And a negative result does not rule the disease out. Read more: Autoimmune risk and what modifies it.
Diagnosis and disease-modifying treatment belong with rheumatology. We will say so plainly, not blur the line. What an interventional pain practice adds is spotting the pattern in someone who has not been evaluated. It also treats the mechanical pain sources that build up alongside the disease. That helps patients whose inflammation is already controlled but who still hurt. Read more: Pain is a signal, not the disease.
Because disease activity and pain are linked but not the same. A pooled analysis of 14 studies found anti-TNF therapy sharply improved disease activity and function. But it had no significant effect on X-ray progression. The inflammation and the structural damage can be separated. Lasting pain in one spot in a treated patient is often a separate mechanical source that can be tested. It is not always a sign the medicine has failed. Read more: Why pain treatments stop working.
No — and in this disease that instinct is especially costly. Inflammatory back pain usually improves with movement and worsens with rest. Steady exercise is a core part of long-term care, not an optional extra. What changes is how you exercise, not whether. Read more: Walking as treatment for low back pain.
Treat it as an emergency and go to an emergency department. A long-standing fused spine breaks like a long bone. These fractures are often unstable and easy to miss on plain X-rays. They can involve the spinal cord. New, sharply changed or unusually bad pain after even a minor fall is not something to schedule. Read more: Sudden back pain and vertebral fracture.
Prefer not to fill in a form?
Same-day and emergency appointments are available.