What is Seronegative Spondyloarthropathy?
Seronegative spondyloarthropathies (SpA) is a group of disorders concerning the joints and primarily affecting the spine, which includes the following:
1. Ankylosing spondylitis (AS) – an inflammatory disease that can make some of your vertebrae (the small bones that form your spine) fuse together.
2. Psoriatic arthritis (PsA) – a form of arthritis that affects some people that have the skin condition psoriasis.
3. Arthritis associated with inflammatory bowel disease (IBD) – a type of arthritis that can develop in people with conditions like Crohn’s disease or ulcerative colitis.
4. Reactive arthritis – a condition which often occurs following an infection.
5. Undifferentiated SpA: a form of SpA that does not meet the complete criteria for other types of spondyloarthritis.
These conditions have been further identified into three more classes: non-radiographic axial SpA (nr-axSpA; a type of SpA that does not show damage on X-rays), peripheral SpA (affects mainly joints other than the spine), and juvenile-onset SpA (develops in children and adolescents).
SpA disorders share several common symptoms and are linked by similar genetic factors.
What Causes Seronegative Spondyloarthropathy?
There is a well-known link between the occurrence of SpA, a group of inflammatory arthritis conditions, and the presence of the HLA-B27 gene in a population. The strongest relation is found in Ankylosing Spondylitis (AS), a type of arthritis that affects the spine. In the United States, 7% of the general population has the HLA-B27 gene, but it is found in 90% of people diagnosed with AS.
Psoriatic Arthritis (PsA), a type of arthritis that affects some people who have psoriasis, is linked to several HLA molecules, including HLA-B27, HLA-DR7, and HLA-DQ3. In the types of arthritis associated with Inflammatory Bowel Disease (IBD) (Crohn’s disease and ulcerative colitis), the link to the HLA gene is not as strong compared to other types of SpA.
Reactive Arthritis (ReA), which follows an infection in the intestines or urinary tract, has a varying link with the HLA-B27 gene. Studies report that this gene is found in anywhere from less than 50% to around 85% of people with ReA. In those with non-specific SpA and juvenile-onset SpA, HLA-B27 is found in approximately 50% and 60% to 80% of cases, respectively.
Risk Factors and Frequency for Seronegative Spondyloarthropathy
SpA, also known as spondyloarthritis, has a global presence, affecting between 0.5% to 1.9% of the population. The most common forms of SpA in the United States are AS (Ankylosing Spondylitis) and non-radiographic axial SpA, making up between 0.7% to 1.4% of cases. Another condition, PsA, or Psoriatic Arthritis, has an equal impact on both men and women, with an occurrence rate of 0.1% to 0.2% and a newly diagnosed case rate of 0.006%. Of those who suffer from psoriasis, anywhere from 4% to 30% will also deal with PsA. Another variant, IBD-related arthritis, is found in 3% to 13% of patients with either ulcerative colitis or Crohn’s disease. Lastly, ReA (Reactive Arthritis), while less common, is usually caused by certain organisms such as Chlamydia, Campylobacter, Salmonella, Shigella, and Clostridium difficile – with a global prevalence of around 0.03% to 0.04%.
Signs and Symptoms of Seronegative Spondyloarthropathy
When checking for inflammatory back and joint pain, doctors tend to ask questions about a person’s medical history. This can help tell if the pain is related to inflammation. For example, the pain could become worse with rest and feel much better with activity, or be associated with stiffness that lasts over an hour in the morning. Anti-inflammatory drugs (NSAIDs) are likely to greatly reduce these symptoms.
People suffering from axial SpA (a form of joint disease) often experience chronic lower back pain for more than three months which starts subtly before they turn 45. Tests like the Schober’s test (which checks lower back flexibility) and the occiput to wall test (which measures upper back and neck mobility) should be a regular part of the physical examination for these patients.
Those with peripheral SpA (another form of joint disease) usually experience sudden joint pain, particularly in the knees and ankles, enthesitis (inflammation at points where tendons or ligaments insert into the bone), and dactylitis (swelling of an entire digit – a finger or toe). It’s worth noting that this joint pain is typically not the same in all joints. Hallmark signs of enthesitis, commonly observed in SpA, are seen at the spot where the calcaneal (heel bone) tendon inserts. This causes tenderness and discomfort when walking.
Not all symptoms relate to the muscles and bones. Some patients may exhibit issues with their eyes, like inflammation (uveitis, iritis, conjunctivitis), occur after or along with stomach or urinary tract infections, or show signs of skin conditions like psoriasis. It’s important to note any family history of SpA or other autoimmune disorders as this can also impact a person’s likelihood of developing these conditions.
Testing for Seronegative Spondyloarthropathy
If you come to the doctor with symptoms like back pain associated with inflammation, the doctor will start with a plain x-ray of your back and pelvis to look at the sacroiliac joints and spine. These are the areas commonly affected by spondyloarthritis (SpA), a type of arthritis that affects the spine. They will also do blood tests to check for markers of inflammation, which should be high if you have SpA.
In more advanced cases of a specific type of SpA, Ankylosing Spondylitis (AS), an x-ray can sometimes show changes to the spine. It might show signs of “shiny corners” (hardening where the spinal disc attaches to the front corner of a spinal bone), a “bamboo spine” (hardening of the spinal discs making the spine look like a bamboo stick), and “squaring” of spinal bones.
If the x-ray doesn’t show clear signs of AS but the doctor still suspects it, they may check if you carry a gene called HLA-B27, which is common in people with AS. They may also consider an MRI, which can help to highlight early signs of inflammation. Some people have non-radiographic axial SpA (nr-axSpA) where there are no clear changes on the x-ray but have other signs of SpA based on blood tests and symptoms.
If you go to the doctor with symptoms like swollen joints, inflammation where tendons or ligaments attach to bone (enthesitis), or inflammation of an entire digit (dactylitis), the doctor will look for signs of other conditions like skin psoriasis, inflammatory bowel disease, or a past infection. If you have any of these conditions, the doctor might diagnose you with psoriatic arthritis (PsA), SpA related to inflammatory bowel disease, or reactive arthritis (ReA).
If none of these conditions are present, the doctor will check for the HLA-B27 gene and other markers of inflammation. They would also take x-rays of the affected joints and check if you have inflammation in your eyes, a condition called uveitis. This is because all these features can be signs of SpA.
Treatment Options for Seronegative Spondyloarthropathy
The main goals of treating SpA, a family of inflammatory diseases, are to alleviate symptoms, lessen physical impairment, and prevent complications caused by the disease. Moving regularly can help strengthen the spine and maintain joint flexibility. Professional physical therapy is often helpful in this.
Usually, the first step of treatment is using a type of medication called Nonsteroidal Anti-inflammatory Drugs (NSAIDs), which help reduce pain and inflammation. If two different NSAIDs don’t work or cause side effects or other health issues, the next steps depend on whether the SpA is affecting the spine (axial disease) or the arms and legs (peripheral disease).
For SpA affecting the spine, next in line are medicines known as biologics, specifically those that inhibit TNF, a protein in the body that causes inflammation. Examples of these drugs include infliximab, etanercept, adalimumab, golimumab, and certolizumab. They have been found to greatly lessen or even remove symptoms. However, they can’t be used if the patient has an active infection, heart failure, lupus, multiple sclerosis, or cancer.
Recently, another biologic has been approved for treating spinal disease: Secukinumab, which is an antibody that inhibits interleukin 17A, another protein causing inflammation. It works well in those who can’t tolerate TNF inhibitors.
Another class of drugs, known as non-biologic DMARDS (disease-modifying anti-rheumatic drugs), are not effective in treating spinal disease, but can help treat peripheral disease. If these don’t work, TNF inhibitors may be used. Sometimes, a combination of biologic and non-biologic DMARDS might be used to control the disease.
Glucocorticoids, another kind of medication, have a limited role in SpA. They can be essential for patients with severe uveitis and IBD-associated arthritis. However, localized glucocorticoid injections should be used very rarely due to the risk of tendon rupture.
It’s important to remember that reactive arthritis (ReA), a type of SpA, is usually a self-limited disease, but it can be treated in a similar manner to other SpA diseases. Surgery is considered only as a last resort when all other treatment options have been exhausted.
Progress of the disease is measured by patient history, physical exam, assessing inflammation markers, and repetitive imaging.
What else can Seronegative Spondyloarthropathy be?
Doctors might be looking at a range of conditions if you have problems with your back, feet, or bones. These conditions might include:
- Birth defects affecting the spine
- Degenerative Disk Disease, a condition where the cushioning discs between your spine’s vertebrae break down with age
- Diabetic Foot Ulcers – open sores or wounds that occur in people with diabetes
- Herniated Nucleus Pulposus, also known as a slipped disk
- Heterotopic Ossification – a condition where bone grows in the wrong place
- Kyphosis – a hunched or rounded back
- Lumbar Disc Disease – trouble with the discs in your lower back
- Lumbar Spondylosis – arthritic changes in your lower back
- Osteoarthritis – a type of arthritis that affects your bones
- Osteofibrous Dysplasia – a rare disorder where your bone tissue doesn’t grow properly
