Overview Of Spondyloarthritis: A Family Of Related Diseases

Similarities And Differences Between Six Conditions - A Q&A With Dr. Jessica Walsh

Editor's Note: The following is a Q&A on spondyloarthritis with Dr. Jessica Walsh.

Dr. Jessica Walsh is a rheumatologist at the University of Utah as well as the Veterans Affairs Medical Center in Salt Lake City. There, she is also the Director of Spondyloarthritis Clinics, the founder of the Utah Psoriatic Arthritis Initiative, and Principal Investigator for the Program to Understand the Long-term Outcomes in Spondyloarthritis (PULSAR) registry.

Dr. Walsh is a member of the Spondyloarthritis Research & Treatment Network (SPARTAN) and of the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA).

This article originally appeared in SAA's news magazine, Spondylitis Plus.



Q: We hear a few different terms to describe ankylosing spondylitis (AS) and related diseases: Spondyloarthritis, spondyloarthritides and spondyloarthropathy...Is there a difference?

Spondyloarthritis and spondyloarthropathy are often used interchangeably. Some experts prefer the term spondyloarthritis rather than spondyloarthropathy because the ending “arthritis” indicates inflammation of the joint, whereas the ending “arthropathy” can refer to any type of joint disease. Inflammation is a key feature that helps distinguish spondyloarthritis from other types of arthritis, including wear-and-tear arthritis, such as osteoarthritis. Spondyloarthritides is the plural form of spondyloarthritis.

Q: How is this group of diseases related? Why is it sometimes called a "family" of conditions?

These diseases look and behave in similar ways because they share overlapping disease features. Common features of spondyloarthritis include inflammation in the spine, pelvis, other joints, intestine, eyes (iritis/uveitis), and heels [Editor's note: for more information on (iritis/uveitis) and other possible complications of spondyloarthritis, please click here.]. This family of diseases is divided into individual categories according to the predominant disease feature(s). For example, inflammation of the intestine can occur with any type of spondyloarthritis, but is most pronounced in patients with IBD-associated arthritis (also called enteropathic arthritis).

Q: What does "seronegative" mean? How does it relate to this group of diseases?

Seronegative means that specific blood tests used to help diagnose rheumatoid arthritis are negative. In some instances, these blood tests are helpful in determining whether a person has rheumatoid arthritis or spondyloarthritis. In most cases, a diagnosis of spondyloarthritis can be made without these blood tests.

Q: Can you give us a key symptom or "feature" of each of the conditions in this group? What makes each one distinct or different from the others?

Spondyloarthritis (SpA) diseases are grouped or classified in different ways. The two most common ways of classifying spondyloarthritis in adults include:
  • The traditional five groups of ankylosing spondylitis, reactive arthritis, psoriatic arthritis, enteropathic arthritis, and undifferentiated spondyloarthritis.
  • The newer two group classification system of axial spondyloarthritis and peripheral spondyloarthritis.
Traditional SpA Classification System

Ankylosing Spondylitis (AS):

Inflammation in the pelvis and/or spine causes inflammatory back pain. Inflammatory back pain usually starts gradually before the age of 40, tends to improve with activity but not rest, and occurs with stiffness in the morning that lasts at least 30 minutes. The inflammation in the pelvis also causes changes that can be seen on imaging in the sacroiliac joints (joints that connect the tailbone to the pelvis bones).

Reactive Arthritis (ReA):

An infection in the intestine or urinary tract usually occurs before inflammation in the joints.

Juvenile Spondyloarthritis (JSpA):

Symptoms begin in childhood. JSpA can look like any other type of spondyloarthritis. Enthesitis (inflammation where tendons or ligaments meet bone) is often a dominant disease feature.

Arthritis Associated With Inflammatory Bowel Disease (Enteropathic Arthritis - EnA):

Inflammation of the intestine is a predominant feature. Symptoms may include chronic diarrhea, abdominal pain, weight loss, and/or blood in the stool. The most common types of inflammatory bowel disease are Crohn’s, ulcerative colitis, and undifferentiated colitis.

Psoriatic Arthritis (PsA):

PsA frequently causes pain and swelling in the small joints of the hands and feet. Most people with PsA have a psoriasis skin rash. Some people have a “sausage digit” with a toe or finger that swells between the joints as well as around the joints.

Undifferentiated Spondyloarthritis (USpA):

People with USpA have symptoms and disease features consistent with spondyloarthritis, but their disease doesn’t fit into another category of spondyloarthritis. For example, an adult may have iritis, heel pain (enthesitis), and knee swelling, WITHOUT back pain, psoriasis, a recent infection, or intestinal symptoms. This person’s combination of disease features suggests spondyloarthritis, but she doesn’t fit into the categories of ankylosing spondylitis, psoriatic arthritis, reactive arthritis, juvenile spondyloarthritis or IBD-associated arthritis.

Newer SpA Classification System

Axial Spondyloarthritis (AxSpA):

AxSpA causes inflammation in the pelvis and/or spine that typically causes inflammatory back pain. AxSpA is a broad category that includes people with and without characteristic inflammatory changes of the sacroiliac joints seen on Xray.

Doctors classify people as having a certain type of axial spondyloarthritis:

  • Radiographic AxSpA with characteristic Xray changes.
  • Nonradiographic AxSpA without characteristic Xray changes.

Almost all people with ankylosing spondylitis fit into the category of radiographic AxSpA. People with reactive arthritis, enteropathic arthritis, undifferentiated spondyloarthritis, and psoriatic arthritis may fit into the category of either radiographic AxSpA or nonradiographic AxSpA.

Peripheral Spondyloarthritis (pSpA):

Peripheral SpA commonly causes inflammation in joints and/or tendons outside the spine or sacroiliac joints. Commonly involved sites include joints in the hands, wrists, elbows, shoulders, knees, ankles, and feet. Inflammation of the tendons can occur in the fingers or toes (dactylitis) or where tendons and ligaments meet with bone (enthesitis). Almost all people with PsA fit into the pSpA category at some point in their disease. People with reactive arthritis, enteropathic arthritis, and undifferentiated arthritis may also fit into this category.

Many people have or will develop both AxSpA and pSpA. Others have only AxSpA or only pSpA.

Q: Can one of these conditions share symptoms or complications with another one of the conditions? In general terms, do symptoms overlap? If so, how? What are the main similarities - if any?

Absolutely. The main similarities that can occur with any type of spondyloarthritis are:

  • Inflammation in the pelvis and spine that usually causes inflammatory back pain.
  • Pain and/or swelling of any other joint in the body (hips, knees, ankles, feet, hands, wrists, elbows, shoulders etc.)
  • Rapid onset of marked pain and redness in one eye at a time (Uveitis/iritis).
  • Psoriasis skin rash.
  • Inflammation in the intestine (Crohn’s, ulcerative colitis, undifferentiated colitis).
  • Inflammation along the tendons of the finger or toes (sausage digits, also called dactylitis).
  • Inflammation where tendons and ligaments meet the bone (enthesitis). This commonly occurs at the back or bottom of the heel.

Q: Why would a doctor diagnose one form of spondyloarthritis over another?

Doctors classify people as having a certain type of spondyloarthritis according to the predominant disease feature(s). For example a person with psoriasis and joint swelling in the hands and feet will most likely be classified as having psoriatic arthritis. A person with inflammatory back pain and x-ray changes consistent with inflammation in the sacroiliac joints in the pelvis will likely be classified as having ankylosing spondylitis. A person with Crohn’s and swelling in the knees and ankles most likely has IBD-associated arthritis. Sometimes, disease features are equally dominant and a person may fit into more than one type of spondyloarthritis. For example, a person could have psoriasis, inflammation in the pelvis/spine, and Crohn’s disease. This person could correctly be said to have any of the following:

  • Psoriatic arthritis with ankylosing spondylitis and Crohn’s.
  • Ankylosing spondylitis with psoriasis and Crohn’s.
  • IBD-associated arthritis with ankylosing spondylitis and psoriasis.

Q: Can a diagnosis change from, say, undifferentiated spondyloarthritis (USpA) to ankylosing spondylitis or another one of these conditions? Why would this occur?

Yes. The diseases can evolve or change over time, since not all symptoms occur at once. For example, the previously discussed person with USpA with iritis, enthesitis, and knee swelling could develop back pain and inflammatory changes on x-ray that would lead to the diagnosis of ankylosing spondylitis.

Q: How are these conditions treated? Are there any notable differences in treatment such as prescribed medications?

There are several treatment options for various types of spondyloarthritis. The treatments for each disease overlap, but they are not identical. For example, certain treatments may simultaneously help with psoriasis, inflammatory bowel disease, enthesitis, and arthritis. Other treatments may help with one or two disease features, but not the others. There are even some treatments that may help with one disease feature, but make another feature worse. Treatments need to be tailored for each individual, according to the type and severity of specific disease features. Many other factors must also be considered when selecting therapies, including other medical conditions, access to therapies, and the preferences of patients.

Q: Is there a known cause for these diseases?

We know that there are several specific genes that increase the risk of developing spondyloarthritis. HLA-B27 is the best studied gene and it associates most strongly with inflammation in the pelvis (sacroiliac joints) and spine. Most people with HLA-B27 and other high risk genes never develop spondyloarthritis. We don’t yet understand why some people develop disease and others don’t. There are also studies suggesting that things in our environment may cause disease. For example, specific types of infections may trigger disease. However, environmental triggers are not known for most people who develop spondyloarthritis. There is much research that needs to be done to better understand why people get disease.