Patient education: Psoriatic arthritis (Beyond the Basics)

PSORIATIC ARTHRITIS OVERVIEW — Psoriatic arthritis is a type of arthritis that causes joint pain, swelling, and stiffness in some people who have a chronic skin condition called psoriasis. Psoriasis presents as patches of thick, inflamed red skin that are often covered with silvery scales. About 30 percent of people with psoriasis also develop psoriatic arthritis.

Psoriatic arthritis affects men and women equally. Most people who develop psoriatic arthritis have skin symptoms of psoriasis first, followed by arthritis symptoms. However, in about 15 percent of cases, symptoms of arthritis are noticed before psoriasis appears. In another 15 percent of cases, psoriatic arthritis is diagnosed at the same time as psoriasis.

More information about psoriasis is available separately. (See "Patient education: Psoriasis (Beyond the Basics)".)

PSORIATIC ARTHRITIS RISK FACTORS — Researchers have not identified the exact cause of psoriatic arthritis. However, they believe that the disease develops due to a combination of genetic, immunologic, and environmental factors.

Genetic factors — About 40 percent of people with psoriasis or psoriatic arthritis have family members with psoriasis or psoriatic arthritis. The likelihood of developing psoriatic arthritis if a family member has the disease is similar to that observed in psoriasis. The risk of psoriasis in an offspring has been estimated to be 41 percent if both parents are affected, 14 percent if one parent is affected, and 6 percent if one sibling is affected, compared with 2 percent when no parent or sibling was affected.

Genetic researchers have identified areas on certain chromosomes that may increase the risk of developing psoriatic arthritis. Other genetic factors may contribute to the severity of disease.

Immunologic factors — A variety of immune system abnormalities have been noted in people with psoriatic arthritis. For example, people who develop the condition often have higher than normal levels in their blood of certain proteins, called cytokines, which promote inflammation.

Environmental factors — Exposure to certain infections may also contribute to the development of psoriatic arthritis. Some experts believe there is a link between streptococcal infection and the development of psoriasis and psoriatic arthritis, although this link has not been proven. Obesity and the severity of psoriasis are also associated with an increased chance to develop psoriatic arthritis. Psoriatic arthritis also occurs more commonly in people infected with the human immunodeficiency virus (HIV) than in the general population.

Psoriasis frequently appears at sites where there is injury to the skin. This is called the Koebner phenomenon. Some patients develop arthritis in an injured joint. Indeed, physical trauma has been identified as a risk factor for developing psoriatic arthritis among people with psoriasis.

PSORIATIC ARTHRITIS SYMPTOMS — Symptoms of psoriatic arthritis include:

●Pain and tenderness in the joints (picture 1).

●Difficulty moving or stiffness in the joints and/or in the back. About half of all patients have morning stiffness lasting more than 30 minutes.

●Skin patches (also called plaques) that are dry or red, usually covered with silvery-white scales, which may have raised edges (picture 2).

●Nail abnormalities, such as pitted, discolored, or crumbly nails (picture 3).

Some people with psoriatic arthritis experience more difficulty with stiffness and immobility than with joint pain. Fatigue is also common. (See "Clinical manifestations and diagnosis of psoriatic arthritis".)

Patterns of psoriatic arthritis — Psoriatic arthritis tends to affect certain groups of joints. The following terms are used to describe patterns of psoriatic arthritis:

●Distal arthritis – This type of psoriatic arthritis affects the end (distal) joints of the fingers and toes.

●Asymmetric oligoarthritis – This type of psoriatic arthritis affects fewer than five small or large joints in the body but does not necessarily occur on both sides of the body. (For example, a person might experience joint pain in one elbow but not the other.)

●Symmetric polyarthritis – This type of psoriatic arthritis affects five or more joints on both sides of the body (ie, the right and left knee). It produces symptoms similar to those of rheumatoid arthritis.

●Arthritis mutilans – This type of psoriatic arthritis deforms and destroys the joints, and it is often accompanied by a shortening of the affected fingers or toes (picture 4).

●Spondyloarthritis – This type of psoriatic arthritis affects the joints of the spine including the sacroiliac joint (where the spine connects to the pelvis).

Polyarthritis is the most common type of psoriatic arthritis, followed by oligoarthritis. Less than 20 percent of patients experience distal arthritis alone, but those who do may also have spondyloarthritis. Arthritis mutilans, the deforming type of arthritis, can occur along with any other pattern of arthritis, but is much less common than the other types.

The Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA), an international collection of experts on these conditions, has defined psoriatic arthritis as having six domains: peripheral arthritis (joints of the hands, feet, arms, and legs), axial disease (back and neck), enthesitis (inflammation at the points where tendons and ligaments attach to bone), dactylitis (inflammation of the whole digit, eg, finger or toe), skin psoriasis, and nail psoriasis.

Associated problems — In addition to the joint pain and stiffness that psoriatic arthritis causes, there may also be swelling in the areas where tendons attach to bones, a condition called enthesitis. Sites that are commonly involved include the Achilles tendon attachment to the back of the heel, the attachment of plantar fascia (the tendon in the sole of the foot) to the heel, and the area where tendons attach to the pelvic bones. Another condition, tenosynovitis, can occur when the sheaths surrounding certain tendons, especially those in the hands and arms, become swollen and inflamed.

Almost half of people with psoriatic arthritis also experience dactylitis, which causes an entire finger or toe to swell (sometimes called sausage finger or toe). Dactylitis may be associated with progressive joint damage. People with psoriatic arthritis sometimes develop swelling of the hands and feet that is not limited to the joints. This swelling may occur before any joint symptoms of psoriatic arthritis are noted.

Eighty to 90 percent of people with psoriatic arthritis have nail problems. They may develop pitted nails, which look as if someone has taken a pin and pricked the nail several times, or there may be early separation of the nail from the nail bed. The severity of a person's nail problems is often similar to the severity of the skin and joint problems (picture 3).

In some cases, people with psoriatic arthritis also experience eye problems. Inflammation of the structures of the eye can cause eye pain and redness and is referred to as uveitis or iritis.

Like patients with psoriasis, patients with psoriatic arthritis may be at increased risk of heart disease or stroke; certain medicines and lifestyle changes might help decrease this risk. Obesity, type 2 diabetes, and metabolic syndrome are also common in people with psoriasis and psoriatic arthritis, and obesity is a risk factor for both of these disorders (see 'Psoriatic arthritis risk factors' above). Patients with psoriasis and psoriatic arthritis often suffer from anxiety, depression, and sleep disorders, all of which may interfere with treatment response. (See "Patient education: Metabolic syndrome (Beyond the Basics)".)

PSORIATIC ARTHRITIS DIAGNOSIS — Health care providers diagnose psoriatic arthritis by obtaining the medical history, performing a physical examination, and taking x-rays of the joints to check for inflammation and joint damage. Blood tests or joint fluid tests may be done to rule out other diseases, such as rheumatoid arthritis and gout.

In some cases, a magnetic resonance imaging test (MRI), musculoskeletal ultrasound, or technetium bone scan may be performed to detect joint and soft-tissue inflammation that cannot be seen on x-rays. Because psoriatic arthritis may be associated with a loss in bone mineral density, tests may also be used to determine if you are at risk for osteoporosis or have an increased risk of bone fractures. (See "Patient education: Bone density testing (Beyond the Basics)".)

Psoriatic arthritis may be confused with other forms of arthritis, such as rheumatoid arthritis, gout, and, occasionally, osteoarthritis. However, the skin lesions, nail problems, and specific patterns of inflammation observed in psoriatic arthritis allow clinicians to differentiate it from other forms of inflammatory arthritis.

PSORIASIS TREATMENT — Psoriatic skin disease may be treated with topical applications (creams or lotions) or phototherapy. Skin problems that are resistant to topical therapy may require the use of oral treatments (pills). Patients with moderate to severe psoriasis may require treatment with biologic agents. (See "Patient education: Psoriasis (Beyond the Basics)".)

Although effective in controlling the skin symptoms in most patients, none of these treatments work in all patients. Moreover, none can cure psoriasis; most patients have a flare of symptoms if treatment is discontinued. Thus, prolonged therapy is generally required.

PSORIATIC ARTHRITIS TREATMENT — Psoriatic arthritis treatment can help to relieve joint pain and stiffness, as well as the other symptoms of psoriasis. Lifestyle changes can help; many different medications are available as well. Some of the most common approaches are discussed below; your doctor will work with you to figure out the right medication(s) and plan for you based on your symptoms, severity of disease, and preferences. (See "Treatment of psoriatic arthritis".)

Lifestyle changes — In many cases, weight loss can help. Up to 40 percent of psoriatic arthritis patients are obese. Several studies have demonstrated that weight loss can improve response to medical treatments for both psoriasis and psoriatic arthritis.

Weight loss of 10 percent or more of body weight in obese patients can dramatically improve response to treatments. The type of diet is not as important as the weight loss, but you should talk with your doctor about the most appropriate approach to weight loss for you. A combination of exercise and weight loss may also lessen the chance of developing diabetes and improve cardiovascular health in people with psoriatic arthritis.

Treatments such as heat, exercise, and physical therapy may also help to relieve the pain and stiffness associated with psoriatic arthritis. A separate article discusses exercise and arthritis. In particular, interval training was shown to substantially decrease fatigue in patients with psoriatic arthritis. (See "Patient education: Arthritis and exercise (Beyond the Basics)".)

Nonsteroidal antiinflammatory drugs — Nonsteroidal antiinflammatory drugs (NSAIDs) can help to control inflammation and to relieve the pain of psoriatic arthritis. NSAIDs must be taken continuously and at a sufficient dose to have an antiinflammatory effect.

NSAIDs must usually be taken for several weeks before their full degree of effectiveness as an antiinflammatory is known. If the initial dose of an NSAID does not improve symptoms, your doctor may recommend increasing the dose gradually or switching to another NSAID.

●Nonselective NSAIDs include over-the-counter drugs, such as aspirin, ibuprofen, and naproxen, and a number of prescription-strength NSAIDs.

●Selective NSAIDs (also called cyclooxygenase [COX]-2 inhibitors) are as effective as nonselective NSAIDs and are less likely to cause gastrointestinal injury and side effects. Celecoxib (brand name: Celebrex) is the only COX-2 inhibitor available in the United States.

Detailed information about NSAIDs is available in a separate article. (See "Patient education: Nonsteroidal antiinflammatory drugs (NSAIDs) (Beyond the Basics)".)

Glucocorticoid injections — Glucocorticoids, also called steroids, can suppress inflammation and can relieve pain when injected into affected joints. Oral glucocorticoids are not usually recommended for people with psoriatic arthritis because they may cause a severe form of skin psoriasis. They are also associated with an increased risk of developing a number of unwanted side effects including weight gain, increased cardiovascular risk, and diabetes.

Joint injections have few side effects, but some people experience a brief flare of pain after an injection. There is also a very small risk of joint infection.

Methotrexate — Methotrexate (MTX) is a "conventional," "nonbiologic" disease-modifying antirheumatic drug (DMARD). It reduces excessive production of skin cells and may also suppress the immune system. It is often recommended for people with multiple swollen joints caused by psoriatic arthritis. Some people need to take a medication other than MTX because their condition affects the sacroiliac joints (the joints that connect the bottom of the spine to the pelvis) or spine, or because their skin disease does not respond adequately to MTX. Also, MTX may not be recommended, or may need to be prescribed with close monitoring, in people who are obese or have diabetes.

MTX is usually taken once per week as pills or by injection. Treatment with higher doses may require that it be injected under the skin, which may be done by a patient or family member.

Taking folic acid or folinic acid can reduce the risk of certain methotrexate side effects, including risk of liver problems related to methotrexate. Patients who use methotrexate should not drink alcohol. The most serious potential side effects of methotrexate include liver toxicity, lung disease, and bone marrow suppression. (See "Patient education: Disease-modifying antirheumatic drugs (DMARDs) in rheumatoid arthritis (Beyond the Basics)".)

Alternatives to methotrexate — If you are unable to take methotrexate, or if it does not work well enough to relieve your symptoms, your doctor might suggest another medication. Options include:

●Leflunomide – Leflunomide (sample brand name: Arava) is a DMARD that can improve both skin and joint disease symptoms. (See "Patient education: Disease-modifying antirheumatic drugs (DMARDs) in rheumatoid arthritis (Beyond the Basics)".)

Possible side effects include diarrhea and elevated liver enzymes, and only about 40 percent of people with psoriatic arthritis benefit from this treatment. Experts may recommend leflunomide if you have not adequately responded to or have had side effects with methotrexate.

●Sulfasalazine – Sulfasalazine (sulphasalazine, salazopyrin) is a DMARD that may be effective for the joint pain and skin lesions associated with psoriatic arthritis.

However, not all patients benefit from sulfasalazine, and many patients cannot tolerate it due to gastrointestinal side effects. Patients who are allergic to sulfa drugs should not use sulfasalazine. (See "Patient education: Sulfasalazine and the 5-aminosalicylates (Beyond the Basics)".)

●Cyclosporine – Cyclosporine is a drug that suppresses the immune system and is also used to treat severe psoriasis and psoriatic arthritis. It was used more in the past, before the availability of the tumor necrosis factor (TNF) inhibitors, but still may be helpful for some people with psoriatic arthritis. It may take three to four months before a response is seen. Adding cyclosporine to methotrexate may be more effective than either treatment alone. Side effects of cyclosporine can include reduced kidney function and high blood pressure.

●Apremilast – Apremilast (brand name: Otezla) is a medication for psoriatic arthritis that comes in pill form. People taking apremilast should have their weight monitored regularly because the medication can cause significant weight loss. Use of apremilast has also been associated with an increase in reports of depression compared with placebo, but it does not cause significant laboratory abnormalities. This medication has not been demonstrated to inhibit joint damage.

Tumor necrosis factor (TNF) inhibitors — TNF-alpha inhibitors are among the group of drugs called "biologics," "biologic DMARDs," or "biologic response modifiers." These drugs interfere with inflammation and the immune response; they may be used if methotrexate (or another nonbiologic DMARD) is ineffective, or as first-line therapy in people whose psoriatic arthritis is severe and interferes with their ability to function, and in those with arthritis affecting the sacroiliac joint or spine. Drugs in this class include proteins that interfere with the actions of TNF, such as etanercept (brand name: Enbrel), adalimumab (brand name: Humira), infliximab (brand name: Remicade), golimumab (brand name: Simponi), and certolizumab pegol (brand name: Cimzia).

Biologic agents, such as the TNF inhibitors, usually work rapidly, often within two weeks, although they may take three months or more to be fully effective. They may be used alone or in combination with other DMARDs, NSAIDs, and/or glucocorticoid injections. Because of their very high cost, they are often reserved for people who have not responded fully to DMARDs or who cannot tolerate DMARDs in doses large enough to control psoriatic arthritis symptoms.

All biologic agents must be either injected or given intravenously, depending on the medication. Humira, Enbrel, and Cimzia are injected under the skin by the patient, a family member, or a nurse. Intravenous infusion is necessary for Remicade; this is typically done in a doctor's office or an outpatient infusion center and takes one to three hours to complete. Simponi may be given either by injection of by an intravenous infusion (IV).

Other biologic agents — People with severe disease may be treated with other "biologics" instead of TNF inhibitors. Examples include:

●Ustekinumab – A medication called ustekinumab (brand name: Stelara) is sometimes used in people who do not get better with the options listed above. This medication interferes with inflammation by blocking not TNF but another set of proteins involved in the immune response called interleukin (IL)-12 and IL-23. It may be used in patients who do not tolerate or have been unresponsive to anti-TNF agents. It has been shown to slow joint damage. It is injected under the skin by the patient, a family member, or a nurse. Like the TNF inhibitors, this drug increases the risk of infections and might increase the risk of cancer. Ustekinumab may not be effective for back and spinal involvement.

●Secukinumab and ixekizumab – Secukinumab (brand name: Cosentyx) and ixekizumab (brand name: Taltz) are medications which, like ustekinumab, may provide alternatives to TNF inhibitors in some cases. They affect the immune response by interfering with a protein called IL-17. Both are given as an injection under the skin. They increase the risk of infections and might increase the risk of cancer.

●Guselkumab – Guselkumab (brand name: Tremfya) is another option for patients with psoriatic arthritis. This medication inhibits a different protein (IL-23) and is quite effective for both psoriasis and psoriatic arthritis. It is given by injection every eight weeks. Another agent that targets IL-23 (risankizumab [brand name: Skyrizi]) is already approved for both psoriasis and psoriatic arthritis in some countries.

●Abatacept – Abatacept (brand name: Orencia) may be an option in situations where other drugs have been ineffective or cannot be used. This agent is modestly effective for peripheral joint pain and swelling. It has not been particularly effective for psoriasis and the ability to limit X-ray damage has not been studied.

●Tofacitinib and upadacitinib – Tofacitinib (brand name: Xeljanz) and upadacitinib (brand name: Rinvoq) are oral medications available for the treatment of psoriatic arthritis. They work well for the joints, while upadacitinib is more effective for psoriasis than tofacitinib, but these agents may not work as well for the skin as some of the other medications. Both drugs were approved for the treatment of rheumatoid arthritis before their approval for psoriatic arthritis. Concerns have been raised about increased risk of blood clots, malignancies, herpes zoster, and heart disease with these agents, and the labels have important black box (safety) warnings.

WHERE TO GET MORE INFORMATION — Your health care provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for health care professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient education: Psoriasis (The Basics)
Patient education: Psoriatic arthritis in adults (The Basics)
Patient education: Disease-modifying antirheumatic drugs (DMARDs) (The Basics)
Patient education: Psoriatic arthritis in children (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient education: Bone density testing (Beyond the Basics)
Patient education: Psoriasis (Beyond the Basics)
Patient education: Arthritis and exercise (Beyond the Basics)
Patient education: Nonsteroidal antiinflammatory drugs (NSAIDs) (Beyond the Basics)
Patient education: Joint infection (Beyond the Basics)
Patient education: Disease-modifying antirheumatic drugs (DMARDs) in rheumatoid arthritis (Beyond the Basics)
Patient education: Sulfasalazine and the 5-aminosalicylates (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Clinical manifestations and diagnosis of psoriatic arthritis
Treatment of psoriatic arthritis

The following organizations also provide reliable health information.

●The Arthritis Society of Canada

(arthritis.ca)

●Arthritis Foundation

(www.arthritis.org)

●National Library of Medicine

(medlineplus.gov/ency/article/000413.htm, available in Spanish)

●National Psoriasis Foundation

(www.psoriasis.org)