Ankylosing spondylitis: symptoms, diagnosis, treatment and outlook

The NHS says symptoms usually develop slowly over several months or years, and may come and go, improve or get worse over many years. You may not have all of the main symptoms.

• Back pain and stiffness: the NHS says the pain gets better with exercise, but does not improve or gets worse with rest, and is worse in the morning and at night, often waking you during the night.

• Pain in the area around the buttocks.

• Arthritis in other joints such as the hips and knees: pain on moving, tenderness, swelling and warmth.

• Enthesitis: painful inflammation where a tendon or ligament joins a bone, commonly at the top of the shin bone, behind or under the heel, or where the ribs join the breast bone. If the ribs are affected there may be chest pain and difficulty expanding the chest when breathing deeply.

• Fatigue: feeling tired and lacking in energy.

• Other conditions are common, including iritis (acute anterior uveitis, where the front of the eye becomes red and swollen), psoriasis and inflammatory bowel disease.

NICE guideline NG65 sets out when to suspect axial spondyloarthritis. If a person has low back pain that started before the age of 45 and has lasted longer than 3 months, they should be referred to a rheumatologist if 4 or more of the following are also present.

• Low back pain that started before the age of 35.

• Waking during the second half of the night because of symptoms.

• Buttock pain.

• Improvement with movement.

• Improvement within 48 hours of taking NSAIDs.

• A first-degree relative with spondyloarthritis.

• Current or past arthritis, enthesitis or psoriasis.

• NICE says if exactly 3 criteria are present, an HLA-B27 test should be performed and, if positive, the person referred.

The NHS says there is no cure and it is not possible to reverse the damage, but treatment is available to relieve symptoms and help delay progression. In most cases treatment combines exercises, physiotherapy and medicines.

The NHS says to see your GP if you have persistent symptoms. If AS is suspected, you should be referred to a rheumatologist for further tests, which may include blood tests and imaging.

NICE NG65 recommends a plain film X-ray of the sacroiliac joints, where the spine meets the pelvis, and diagnosing ankylosing spondylitis if it shows sacroiliitis meeting the modified New York criteria. If it does not, or an X-ray is not appropriate because the skeleton is not fully mature, it advises an unenhanced MRI using an inflammatory back pain protocol. If the MRI meets the international criteria, non-radiographic axial spondyloarthritis is diagnosed.

NICE says not to rule out spondyloarthritis solely on the presence or absence of any individual sign, symptom or test result, and notes that it can occur in people who are HLA-B27 negative and may be present despite no evidence of sacroiliitis on X-ray. It also says normal CRP and ESR blood markers should not be used to rule out the diagnosis.

In AS, the NHS says changes to the spine can be seen on an X-ray. In the similar condition non-radiographic axial spondyloarthritis, changes cannot be seen on an X-ray but can sometimes be seen on an MRI scan. The symptoms and treatment are similar.

In some people the bones of the spine eventually fuse in a fixed position. NICE says axial spondyloarthritis affects a similar number of women as men.

The NHS says it is not known what causes the condition, but there is thought to be a link with a particular gene variant known as HLA-B27. NICE notes that axial spondyloarthritis can occur in people who are HLA-B27 negative, so the gene is not required for the diagnosis.

NICE lists a family history of spondyloarthritis or psoriasis, and a recent genitourinary infection, among risk factors for spondyloarthritis.

The NHS says the outlook for AS is highly variable. For some people the condition improves after an initial period of inflammation, whereas for others it can get progressively worse. Some people remain fully independent or minimally disabled in the long term, while others eventually become severely disabled because the spinal bones fuse in a fixed position and other joints such as the hips or knees are damaged.

The NHS says AS is associated with an increased risk of weakening of the bones (osteoporosis), spinal fractures and cardiovascular disease. NICE advises discussing cardiovascular risk factors with everyone with spondyloarthritis, considering osteoporosis assessments every 2 years for axial spondyloarthritis, and advising people they may be prone to fractures and to seek advice after falls or trauma, especially if pain increases.

NICE advises that people with spondyloarthritis are told about the possibility of flare episodes and extra-articular symptoms, and that a flare management plan be considered, tailored to the individual. Such a plan includes access to care during flares, self-care such as exercises and stretching, and managing the impact on work and daily life.

The NHS signposts the National Axial Spondyloarthritis Society (NASS) for information on living with the condition, including working, travelling and driving.

On the NHS, a GP refers people with suspected AS to a rheumatologist, and care often includes specialist physiotherapy and, where needed, biologic medicines under NICE criteria.

Private rheumatology consultations can speed assessment and MRI. Biologic medicines started privately may have different funding and monitoring arrangements, so ask how they would be supplied and supervised, and keep your GP informed.