Spondyloarthritis (SpA), also known as spondyloarthropathy, is a collection of

syndromes A syndrome is a set of medical signs and symptoms which are correlated with each other and often associated with a particular disease or disorder. The word derives from the Greek σύνδρομον, meaning "concurrence". When a syndrome is paire ...

connected by genetic predisposition and clinical symptoms. The best-known subtypes are enteropathic arthritis (EA),

psoriatic arthritis Psoriatic arthritis (PsA) is a long-term inflammatory arthritis that may occur in some people affected by the autoimmune disease psoriasis. The classic features of psoriatic arthritis include dactylitis (sausage-like swelling of the fingers ...

(PsA),

ankylosing spondylitis Ankylosing spondylitis (AS) is a type of arthritis from the disease spectrum of axial spondyloarthritis. It is characterized by long-term inflammation of the joints of the spine, typically where the spine joins the pelvis. With AS, eye and bow ...

(AS), and

reactive arthritis Reactive arthritis, previously known as Reiter's syndrome, is a form of inflammatory arthritis that develops in response to an infection in another part of the body (cross-reactivity). Coming into contact with bacteria and developing an infect ...

(ReA). Symptoms of spondyloarthritis include

back pain Back pain (Latin: ''dorsalgia'') is pain felt in the back. It may be classified as neck pain (cervical), middle back pain (thoracic), lower back pain (lumbar) or coccydynia (tailbone or sacral pain) based on the segment affected. The lumbar area ...

arthritis Arthritis is a general medical term used to describe a disorder that affects joints. Symptoms generally include joint pain and stiffness. Other symptoms may include redness, warmth, Joint effusion, swelling, and decreased range of motion of ...

, and

enthesitis Enthesitis is inflammation of the entheses (singular: enthesis), the sites where tendons, ligaments and joint capsules attach to bones. It is a type of enthesopathy, meaning any pathologic condition of the entheses, with or without inflammati ...

, inflammation at bone-adhering ligaments,

tendon A tendon or sinew is a tough band of fibrous connective tissue, dense fibrous connective tissue that connects skeletal muscle, muscle to bone. It sends the mechanical forces of muscle contraction to the skeletal system, while withstanding tensi ...

s, or joint capsules. Spondyloarthritis is caused by a combination of genetic and environmental factors. It is associated with intestinal inflammation, with a connection between

Crohn's disease Crohn's disease is a type of inflammatory bowel disease (IBD) that may affect any segment of the gastrointestinal tract. Symptoms often include abdominal pain, diarrhea, fever, abdominal distension, and weight loss. Complications outside of the ...

and

. Reactive arthritis is primarily caused by gastrointestinal, genitourinary, respiratory infections, and genetic factors. Spondyloarthritis is diagnosed based on symptoms and imaging. Early diagnosis criteria use genetic testing and more advanced forms of medical imaging. Spondyloarthritis is categorized into two groups based on the Assessment of SpondyloArthritis International Society (ASAS) criteria: primarily axial involvement and predominantly peripheral manifestations. Non-steroidal anti-inflammatory drugs (NSAIDs) are administered first for active axial signs of spondyloarthritis. If NSAIDs are contraindicated or cause side effects, TNF blockers are used. Traditional

disease-modifying antirheumatic drug Disease-modifying antirheumatic drugs (DMARDs) comprise a category of otherwise unrelated disease-modifying drugs defined by their use in rheumatoid arthritis to slow down disease progression. The term is often used in contrast to nonsteroida ...

s (DMARDs) are not used for people without peripheral disease signs.

Signs and symptoms

In all subtypes of spondyloarthritis, inflammatory

and/or asymmetrical

, mainly affecting the lower limbs, are the most common symptoms. Another characteristic is

, which is inflammation at the locations where

ligament A ligament is a type of fibrous connective tissue in the body that connects bones to other bones. It also connects flight feathers to bones, in dinosaurs and birds. All 30,000 species of amniotes (land animals with internal bones) have liga ...

s, or

joint capsule In anatomy, a joint capsule or articular capsule is an envelope surrounding a synovial joint. Sacroiliitis symptoms

Inflammatory

associated with

usually starts slowly, has a dull feel to it, and spreads into the gluteal areas. Back pain has a nocturnal component, gets better with movement, and is worse in the morning. Axial arthritis may begin in the

sacroiliac joint The sacroiliac joint or SI joint (SIJ) is the joint between the sacrum and the ilium bones of the pelvis, which are connected by strong ligaments. In humans, the sacrum supports the spine and is supported in turn by an ilium on each side. The ...

s and work its way up to the

cervical spine In tetrapods, cervical vertebrae (: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In sauro ...

over time. Spinal abnormalities such as flattening of the lumbar lordosis, exaggeration of the thoracic kyphosis, and hyperextension of the

lead to limited spinal motion. Hip and shoulder

can occur in some people with

, usually early in the course of the illness. Usually, the other peripheral joints start to be affected later. Most frequently, there is an asymmetrical involvement of the lower extremities.

Reactive arthritis Reactive arthritis, previously known as Reiter's syndrome, is a form of inflammatory arthritis that develops in response to an infection in another part of the body (cross-reactivity). Coming into contact with bacteria and developing an infect ...

is an aseptic arthritis caused by an infectious pathogen found outside the joint. Particularly affecting the joints in the lower limbs, the arthritis is usually oligoarticular. In most cases, the condition develops quickly; two to four joints may swell and hurt in an uneven manner within a few days. Inflammatory

and dactylitis are also prevalent.

Psoriatic arthritis Psoriatic arthritis (PsA) is a long-term inflammatory arthritis that may occur in some people affected by the autoimmune disease psoriasis. The classic features of psoriatic arthritis include dactylitis (sausage-like swelling of the fingers ...

is known to present in five distinct patterns: oligoarticular (affecting four or fewer joints); polyarticular (affecting five or more joints); prominent distal interphalangeal (DIP) joint involvement;

arthritis mutilans Arthritis mutilans is a rare medical condition involving severe inflammation damaging the joints of the hands and feet, and resulting in deformation and problems with moving the affected areas; it can also affect the spine. As an uncommon arthropa ...

; and psoriatic

spondylitis Spondylitis is an inflammation of the vertebrae. It is a form of spondylopathy. In many cases, spondylitis involves one or more vertebral joints, as well, which itself is called spondylarthritis. __TOC__ Types Pott disease is a tuberculous d ...

. More than 70% of cases follow the oligoarticular pattern. Distal joints are frequently impacted by psoriatic arthritis, which is typically asymmetrical. Up to 20% of people with

inflammatory bowel disease Inflammatory bowel disease (IBD) is a group of inflammatory conditions of the colon and small intestine, with Crohn's disease and ulcerative colitis (UC) being the principal types. Crohn's disease affects the small intestine and large intestine ...

(IBD) develop spondyloarthropathy. Those with

are more likely to have this association than those with

ulcerative colitis Ulcerative colitis (UC) is one of the two types of inflammatory bowel disease (IBD), with the other type being Crohn's disease. It is a long-term condition that results in inflammation and ulcers of the colon and rectum. The primary sympto ...

. Arthritis may appear before bowel disease. Usually, the lower extremities are asymmetrically affected by arthritis. The arthritis typically manifests abruptly and follows a migratory pattern. In those who do not fit the criteria for any of the well-established spondyloarthropathies, the term "undifferentiated spondyloarthropathy" is used to characterize the signs of spondyloarthritis. A tiny percentage of these eventually experience a characterized spondyloarthritis, but most experience more general symptoms such as dactylitis,

, unilateral or alternating buttock pain, inflammatory

, and occasionally extra-articular symptoms.

Causes

Spondyloarthritis is caused by a complicated combination of genetic polymorphisms and environment. The relative contributions of genes and environment may differ across different types of spondyloarthritis.

Risk factors

Microscopically visible ileal inflammation is seen in about 50% of people with spondyloarthritis and

during ileocolonoscopy. There seems to be an immunological connection between the gut inflammation observed in

and

. It is known that, in comparison to healthy controls, people with ankylosing spondylitis and those related to them have higher intestinal permeability.

Triggers

The majority of organisms responsible for

are gastrointestinal pathogens, such as '' Shigella flexneri'', ''

Clostridioides difficile ''Clostridioides difficile'' ( syn. ''Clostridium difficile'') is a bacterium known for causing serious diarrheal infections, and may also cause colon cancer. It is known also as ''C. difficile'', or ''C. diff'' (), and is a Gram-positive spec ...

'', '' Yersinia enterocolitica'' and '' Yersinia pseudotuberculosis'', ''

Campylobacter jejuni ''Campylobacter jejuni'' is a species of pathogenic bacteria that is commonly associated with poultry, and is also often found in animal feces. This species of microbe is one of the most common causes of food poisoning in Europe and in the US, w ...

'' and ''

Campylobacter coli ''Campylobacter coli'' is a Gram-negative, microaerophilic, endospore, non-endospore-forming, spiral bacteria, S-shaped bacterial species within genus ''Campylobacter''. In humans, ''C. coli'' can cause campylobacteriosis, a diarrhoeal disease ...

'', and ''Salmonella'' spp. Genitourinary and respiratory infections, such as ''

Chlamydia trachomatis ''Chlamydia trachomatis'' () is a Gram-negative, Anaerobic organism, anaerobic bacterium responsible for Chlamydia infection, chlamydia and trachoma. ''C. trachomatis'' exists in two forms, an extracellular infectious elementary body (EB) and an ...

'' and '' Chlamydia pneumoniae'', have also been linked to reactive arthritis.

Genetics

Given the well-established familial aggregation and the concordance rate of up to 63% in identical twins (vs 23% in nonidentical twins), it is evident that genetic variables play a role in the susceptibility to

. There is limited research on familial aggregation in other forms of spondyloarthritis. HLA-B27 is a polymorphic form of the

HLA-B HLA-B (major histocompatibility complex, class I, B) is a human gene that provides instructions for making a protein that plays a critical role in the immune system. HLA-B is part of a family of genes called the human leukocyte antigen (HLA) comp ...

molecule found in up to 95% of people with

of European ancestry, 70% with

, 60% with psoriatic

, 25% with peripheral

, and 70% with

associated with

Mechanism

The arthritogenic-peptide theory is the classic pathophysiological paradigm for spondyloarthritis. It argues that HLA-B27 displays self-peptides that resemble pathogen-derived peptides to

CD8 CD8 (cluster of differentiation 8) is a transmembrane protein, transmembrane glycoprotein that serves as a co-receptor for the T-cell receptor (TCR). Along with the TCR, the CD8 co-receptor plays a role in T cell Cell signaling, signaling and aid ...

-restricted

T cell T cells (also known as T lymphocytes) are an important part of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell receptor (TCR) on their cell ...

s. Two other theories have been proposed to explain HLA-B27's function. They suggest that HLA-B27's genesis may be autoinflammatory rather than

autoimmune In immunology, autoimmunity is the system of immune responses of an organism against its own healthy cells, tissues and other normal body constituents. Any disease resulting from this type of immune response is termed an " autoimmune disease" ...

, as it plays a part in initiating innate immune responses instead of its traditional function of presenting antigens. According to the first hypothesis, HLA-B27 heavy chains devoid of β2 microglobulin can form disulphide-linked homodimers that are produced at the cell surface and can be recognized directly by

KIR3DL2 Killer cell immunoglobulin-like receptor 3DL2 is a protein that in humans is encoded by the ''KIR3DL2'' gene. Structure Killer cell immunoglobulin-like receptors (KIRs) are transmembrane glycoproteins expressed on natural killer (NK) cells ...

killer

immunoglobulin An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as pathogenic bacteria, bacteria and viruses, includin ...

-like receptors, regardless of the associated

peptide Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty am ...

. According to the second hypothesis, the B pocket's Cys 67 residue causes HLA-B27 heavy-chain misfolding in the endoplasmic reticulum before assembling into complexes with peptide and β2 microglobulin. As a result, the

unfolded protein response The unfolded protein response (UPR) is a cellular stress response related to the endoplasmic reticulum (ER) stress. It has been found to be conserved between mammalian species, as well as yeast and worm organisms. The UPR is activated in response t ...

(UPR) modifies the

immune cells White blood cells (scientific name leukocytes), also called immune cells or immunocytes, are cells of the immune system that are involved in protecting the body against both infectious disease and foreign entities. White blood cells are genera ...

cytokine Cytokines () are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are produced by a broad range of cells, including immune cells like macrophages, B cell, B lymphocytes, T cell, T lymphocytes ...

output and reactivity to various innate immunological stimuli.

Diagnosis

Spondyloarthritis is primarily diagnosed, or at least first suspected, based on clinical factors. According to the current criteria for

, a person must exhibit clinical symptoms of inflammatory

and limited spinal mobility together with radiological sacroiliitis. But many people with inflammatory back pain may have no radiographic evidence of sacroiliitis since up to 10 years might pass between the onset of inflammatory back pain and the development of radiographic sacroiliitis. Criteria for the early diagnosis of axial spondyloarthritis have been developed in light of the emergence of effective treatments. These criteria consider the added value of HLA-B27 testing, as well as current advancements in

MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and rad ...

scanning.

Imaging is crucial to the spondyloarthritis diagnosis process. The most distinctive radiographic observation is the sacroiliac (SI) joints' erosion,

ankylosis Ankylosis () is a stiffness of a joint due to abnormal adhesion and rigidity of the bones of the joint, which may be the result of injury or disease. The rigidity may be complete or partial and may be due to inflammation of the Tendon, tendinous ...

, and sclerosis. There must be clear evidence of sacroiliitis (at least grade 2 bilaterally or grade 3 unilaterally) on the radiographs to diagnose

. When axial spondyloarthritis is suspected,

radiographs are still the initial imaging approach. If radiographs clearly show sacroiliitis, then no more diagnostic imaging is required. But because structural change seen on

radiographs Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical ("diagnostic" radiography and "therapeu ...

can take months or years to emerge, normal radiographs or worrisome abnormalities only warrant additional diagnostic imaging in the context of suggestive clinical symptoms or findings. Furthermore, reading

radiographs can be difficult and dependent on several variables, such as the image quality, the radiological technique, the reader's background, and variations in sacroiliac anatomy. A challenge associated with radiographic imaging is the typical ten-year lag between the beginning of inflammatory

and the development of radiographic sacroiliitis.

imaging of the spine and

entheses The enthesis (plural entheses) is the connective tissue which attaches tendons or ligaments to a bone. There are two types of entheses: ''Fibrous tissue, fibrous entheses'' and ''fibrocartilaginous entheses''. In a fibrous enthesis, the collage ...

has made it possible to distinguish between inflammatory spinal lesions associated with

and those unrelated to it earlier than is feasible with traditional radiography. It has also allowed for accurate anatomical description of spinal components. The only imaging modality that can precisely identify and evaluate spinal inflammation at this time is

magnetic resonance imaging Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and ...

(MRI) of the sacroiliac joints and spine. It is also being developed as a gauge of disease activity and response to treatment. When evaluating someone with

, plain radiographs of the hands and feet are very beneficial. Seventy-five percent of those with

have radiographic abnormalities of the peripheral joints, such as soft tissue swelling, erosions, periarticular

osteopenia Osteopenia, known as "low bone mass" or "low bone density", is a condition in which bone mineral density is low. Because their bones are weaker, people with osteopenia may have a higher risk of fractures, and some people may go on to develop o ...

, periostitis, and narrowing of the joint space. Aggressive psoriatic arthritis erosions can result in the articular surface of the proximal bone of the joint being destroyed and taking on the look of a "pencil in cup." Laboratory abnormalities in spondyloarthritis are nonspecific and less effective for diagnosing a specific disease than clinical presentation. Normochromic normocytic

anemia Anemia (also spelt anaemia in British English) is a blood disorder in which the blood has a reduced ability to carry oxygen. This can be due to a lower than normal number of red blood cells, a reduction in the amount of hemoglobin availabl ...

, increased C reactive protein, and

erythrocyte sedimentation rate The erythrocyte sedimentation rate (ESR or sed rate) is the rate at which red blood cells in anticoagulated whole blood descend in a standardized tube over a period of one hour. It is a common hematology test, and is a non-specific measure of in ...

are frequently present nonspecific indicators. Testing for the

human leukocyte antigen The human leukocyte antigen (HLA) system is a complex of genes on chromosome 6 in humans that encode cell-surface proteins responsible for regulation of the immune system. The HLA system is also known as the human version of the major histo ...

(HLA) can be the most beneficial laboratory investigation. Since only 5% of those with HLA-B27 in the general population will develop

, the correlation between HLA-B27 and the prevalence of spondyloarthritis is weak. Therefore, the illness prevalence in a particular population must be taken into account when interpreting results from HLA-B27 testing.

Classification

Spondyloarthritis is classified into two categories based on the Assessment of SpondyloArthritis International Society (ASAS) classification criteria: primarily axial involvement and predominantly peripheral manifestations.

Axial spondyloarthritis

A person must meet two requirements to be considered for a diagnosis of axial spondyloarthritis: they must be under 45 years old and have experienced

of any kind for at least three months. The second step comprises two sections that are assessed independently according to the existence of either sacroiliitis on imaging or human leukocyte antigen (HLA) B27: * HLA-B27-positive people — To diagnose axial spondyloarthritis in those who test positive for HLA-B27, at least two more spondyloarthritis symptoms from the list below must be present. * Sacroiliitis on imaging — When sacroiliitis is diagnosed in those with structural alterations on plain radiographs or subchondral bone marrow edema (BME) on

, at least one additional sign of spondyloarthritis from the list below should be present. Spondyloarthritis features: * Inflammatory

— Several definitions have been put forth for inflammatory back pain. Inflammatory back pain is characterized by the presence of four or more of the following five factors: ** Onset at <40 years old. ** Insidious onset. ** Improved with exercise. ** Not improved by rest. ** Pain at night. *

Arthritis Arthritis is a general medical term used to describe a disorder that affects joints. Symptoms generally include joint pain and stiffness. Other symptoms may include redness, warmth, Joint effusion, swelling, and decreased range of motion of ...

. * Heel

. *

Uveitis Uveitis () is inflammation of the uvea, the pigmented layer of the eye between the inner retina and the outer fibrous layer composed of the sclera and cornea. The uvea consists of the middle layer of pigmented vascular structures of the eye and ...

. * Dactylitis. *

Psoriasis Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by patches of abnormal skin. These areas are red, pink, or purple, dry, itchy, and scaly. Psoriasis varies in severity from small localized patches to complete b ...

. *

Inflammatory bowel disease Inflammatory bowel disease (IBD) is a group of inflammatory conditions of the colon and small intestine, with Crohn's disease and ulcerative colitis (UC) being the principal types. Crohn's disease affects the small intestine and large intestine ...

. * Good response to

nonsteroidal anti-inflammatory drug Non-steroidal anti-inflammatory drugs (NSAID) are members of a Indication (medicine), therapeutic drug class which Analgesic, reduces pain, Anti-inflammatory, decreases inflammation, Antipyretic, decreases fever, and Antithrombotic, prevents bl ...

s ( NSAIDs). * Family history of spondyloarthritis. * Elevated

C-reactive protein C-reactive protein (CRP) is an annular (ring-shaped) pentameric protein found in blood plasma, whose circulating concentrations rise in response to inflammation. It is an acute-phase protein of hepatic origin that increases following interleukin ...

(CRP).

Peripheral spondyloarthritis

The initial requirement is that a person have at least one of the following three findings: *

. *

Enthesitis Enthesitis is inflammation of the entheses (singular: enthesis), the sites where tendons, ligaments and joint capsules attach to bones. It is a type of enthesopathy, meaning any pathologic condition of the entheses, with or without inflammati ...

. * Dactylitis. If the person meets the previous requirements, they must exhibit at least one of Group A's spondyloarthritis features or two of Group B's spondyloarthritis features. Group A spondyloarthritis features: *

. *

. * Preceding infection. * HLA-B27. * Sacroiliitis on imaging. Group B spondyloarthritis features: *

. *

. * Dactylitis. * Inflammatory

in the past. * Family history of spondyloarthritis.

Treatment

Improving the persons's state (pain, functional impairment, etc.) and preventing further clinical deterioration are the goals of spondyloarthritis treatment. The ASAS has issued guidelines regarding the use of TNF blockers specifically as well as the general care of spondyloarthritis. Non-steroidal anti-inflammatory drugs (NSAIDs) should be administered first to those with active, primarily axial signs of spondyloarthritis. If

NSAID Non-steroidal anti-inflammatory drugs (NSAID) are members of a therapeutic drug class which reduces pain, decreases inflammation, decreases fever, and prevents blood clots. Side effects depend on the specific drug, its dose and duration of ...

medication is contraindicated, does not work, or causes side effects, people are then treated with tumor necrosis factor (TNF) blockers. Because there is insufficient evidence of treatment efficacy, those with axial spondyloarthritis who do not exhibit peripheral disease signs do not receive traditional

s (DMARDs). But if peripheral arthritis is present, those with spondyloarthritis should get treatment with conventional DMARDs before TNF-blocker medication and after the failure of

therapy. According to a recent Cochrane systematic review of published work, supervised group

physiotherapy Physical therapy (PT), also known as physiotherapy, is a healthcare profession, as well as the care provided by physical therapists who promote, maintain, or restore health through patient education, physical intervention, disease preventio ...

is superior to home exercises, individual home-based or supervised exercise programs are preferable to no intervention, and in-patient spondyloarthritis exercise therapy combined with follow-up group physiotherapy is superior to group physiotherapy alone. Recreational exercise, whether performed in a group setting or alone, helps people with

feel less stiff and in pain. Back exercise also helps these people function better, but the effects vary depending on how long the disease has been present. People's health improves when they engage in back exercises five days a week and recreational activity for at least half an hour each day. NSAIDs continue to be the first line of treatment for

, and many people will get adequate symptom relief on their own with just these medications. The best NSAID for treating those with ankylosing spondylitis appears to be tolmetin or

indomethacin Indometacin, also known as indomethacin, is a nonsteroidal anti-inflammatory drug (NSAID) commonly used as a prescription medication to reduce fever, pain, stiffness, and swelling from inflammation. It works by inhibiting the production of pr ...

, although there is insufficient evidence to support this theory in rheumatologic practice. The majority of those with established

peptic ulcer disease Peptic ulcer disease is when the inner part of the stomach's gastric mucosa (lining of the stomach), the first part of the small intestine, or sometimes the lower esophagus, gets damaged. An ulcer in the stomach is called a gastric ulcer, while ...

should take selective COX-2 antagonists. When peripheral arthritis coexists with axial illness, conventional DMARDs such

methotrexate Methotrexate, formerly known as amethopterin, is a chemotherapy agent and immunosuppressive drug, immune-system suppressant. It is used to treat cancer, autoimmune diseases, and ectopic pregnancy, ectopic pregnancies. Types of cancers it is u ...

, sulfasalazine, or

leflunomide Leflunomide, sold under the brand name Arava among others, is an immunosuppressive disease-modifying antirheumatic drug (DMARD), used in active moderate-to-severe rheumatoid arthritis and psoriatic arthritis. It is a pyrimidine synthesis inhib ...

may be useful in treating peripheral spondyloarthritis. These drugs are typically ineffective in treating axial symptoms of spondyloarthritis. After 2000, a number of studies examining the effects of TNF blockers on people with

were published. These studies demonstrated that TNF-blocker therapy improves clinical symptoms, CRP levels, and MRI-detectable inflammation in the spine or sacroiliac joints. These improvements were noted with certolizumab pegol,

etanercept Etanercept, sold under the brand name Enbrel among others, is a biologic medical product that is used to treat autoimmune diseases by interfering with tumor necrosis factor (TNF), a soluble inflammatory cytokine, by acting as a TNF inhibitor. ...

infliximab Infliximab, a chimeric monoclonal antibody, sold under the brand name Remicade among others, is a medication used to treat a number of autoimmune diseases. This includes Crohn's disease, ulcerative colitis, rheumatoid arthritis, ankylosing ...

adalimumab Adalimumab, sold under the brand name Humira and others, is a disease-modifying antirheumatic drug and monoclonal antibody used to treat rheumatoid arthritis, juvenile idiopathic arthritis, psoriatic arthritis, ankylosing spondylitis, Crohn' ...

, and golimumab.

Outlook

The lives of people with

are profoundly affected. According to recent statistics, people with

, particularly those who are older and have had the condition longer, may be more likely than population controls to be work handicapped or not engage in the labor market. Additionally, those with ankylosing spondylitis were more likely to have never married or been divorced. Compared to expectations, women with

were less likely to have had children. People with

experience up to 50% more sick leave episodes, an overall 8% loss of productivity, and a thrice higher rate of disability than the general population. Their overall frequency of disability and economic costs are comparable to those of

rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects synovial joint, joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and h ...

. Furthermore, increasing evidence indicates that cardiovascular illness puts those with ankylosing spondylitis at risk for early death. Early research on the course of

indicated a poor prognosis. But more recent research has shown that the prognosis for

is generally favourable. Within six months of onset, the majority of cases seem to resolve. The prognosis for

is worse than previously thought, according to recent research. It has also been demonstrated that those with

have a higher mortality rate, which is linked to high

, high usage of medications, and early radiographic damage. While not well researched, the prognosis for juvenile spondyloarthritisis is unknown. According to the data available, children who have had a condition for longer than five years are more likely to be impaired. After five years of the illness, the chance of remission was only 17 percent. After ten years of the condition, moderate to severe restriction affects around 60% of children with juvenile spondyloarthritis.

Epidemiology

The prevalence of

and spondyloarthritis, in particular, varies across populations and is similar to that of HLA-B27. The incidence of spondyloarthritis as a disease entity was recorded in only four investigations, and ranged from 0.48/100,000 in

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

to 62.5/100,000 in

Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...

. Data on the prevalence of spondyloarthritis were reported from 16 investigations; the results ranged from 0.01% in

to 2.5% in

Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...

. Those with European heritage have a 0.2% to 0.7% prevalence of

prevalence is unknown and likely varies with time based on endemic rates of the enteric (''

Shigella ''Shigella'' is a genus of bacteria that is Gram negative, facultatively anaerobic, non–spore-forming, nonmotile, rod shaped, and is genetically nested within ''Escherichia''. The genus is named after Kiyoshi Shiga, who discovered it in 1 ...

'', ''

Salmonella ''Salmonella'' is a genus of bacillus (shape), rod-shaped, (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two known species of ''Salmonella'' are ''Salmonella enterica'' and ''Salmonella bongori''. ''S. enterica'' ...

'', ''

Campylobacter ''Campylobacter'' is a type of bacteria that can cause a diarrheal disease in people. Its name means "curved bacteria", as the germ typically appears in a comma or "s" shape. According to its scientific classification, it is a genus of gram-negat ...

'') and sexually acquired (

chlamydia Chlamydia, or more specifically a chlamydia infection, is a sexually transmitted infection caused by the bacterium ''Chlamydia trachomatis''. Most people who are infected have no symptoms. When symptoms do appear, they may occur only several w ...

) infections that cause it. In the general community, 1–3% of people have

psoriasis Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by patches of abnormal skin. These areas are red, pink, or purple, dry, itchy, and scaly. Psoriasis varies in severity from small localized patches to complete b ...

. It is less known how common

is, and it is more common in people with more severe disease; population studies in Caucasians suggest that the prevalence is about 0.1%.

about 400 Caucasians per 100,000 people, with a male–to–female ratio of 1:1. People of Asian and African ancestry rarely experience it. Varying reports have varying risks for

and peripheral arthritis, which may be related to the observer's specialty. 15% to 20% of people with

have spondylitis. Peripheral arthritis is generally less common in those with

(up to 10%) than in those with

(up to 20%), but it is more common in cases where a

rheumatologist Rheumatology () is a branch of medicine devoted to the diagnosis and management of disorders whose common feature is inflammation in the bones, muscles, joints, and internal organs. Rheumatology covers more than 100 different complex diseases, c ...

served as the assessor.

History

Moll and associates first proposed the idea of a collection of similar conditions known as seronegative spondyloarthritides in 1974.

, arthritis associated with

, a subtype of

juvenile idiopathic arthritis Juvenile idiopathic arthritis (JIA), formerly known as juvenile rheumatoid arthritis (JRA), is the most common chronic rheumatic disease of childhood, affecting approximately 3.8 to 400 out of 100,000 children. ''Juvenile'', in this context, ref ...