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Psoriatic Arthritis Factsheet

  • Psoriatic arthritis (PsA) is a systemic , inflammatory disease associated with arthritis and psoriasis1,2
  • PsA is thought to be triggered by both genetic and environmental factors3
  • PsA affects between 50,000 – 156,000 people in the UK4
  • Common symptoms of PsA include fatigue, pain and swelling and scaly spots on the skin5


What is psoriatic arthritis? (PsA)

Psoriatic arthritis (PsA) is a systemic inflammatory disease involving inflammation of the joints (arthritis) which is associated with the skin disorder, psoriasis.1,2 People living with PsA usually experience a combination of both psoriatic and arthritic symptoms causing soft tissue swelling, pain, stiffness and limitation in the use of joints; affecting the knees, elbows, hips and the spine. The inflammation in psoriatic arthritis can also affect the tendons (the fibrous tissue that attaches the muscle to the bone).1,2

How is it caused?

A number of factors are thought to cause PsA including environmental as well as genetic but the exact causes are still unknown. Studies have pointed to psoriasis itself being triggered by skin injuries or streptococcal throat infections causing outbreaks of guttate psoriasis which can in turn lead to chronic plaque psoriasis.3 Psoriasis has also been attributed to certain drugs (i.e. lithium, beta-blockers and corticosteroids) or, stress, smoking, alcohol and HIV infections.3

In some cases of PsA, psoriasis may precede, occur simultaneously to or following the onset of arthritis. In cases of psoriasis following the onset of arthritis, this is often in the context of a family history of psoriasis.1

How common is it?

It is estimated that PsA affects approximately 0.1% to 0.3% of the total population in England and Wales which equates to approximately 50,000 – 156,000 people. Both men and women are susceptible to PsA with the onset of disease usually occurring between the ages of 30 – 55 years.4 It is estimated that 5-7% of the psoriasis patient population has psoriatic arthritis with the propensity of this increasing to 40% in those with severe psoriasis.4

What are the symptoms?

PsA will affect patients in different ways depending on the severity of the disease. The most common symptoms tend to include:5

· Fatigue

· Pain and swelling in more than one joint usually being the wrists, knees, ankles, fingers and toes

· Back pain

· Scaly spots on the scalp, elbows, knees and the lower end of the backbone

· Nail pitting, characterized by the detachment of fingernails and or toenails


Due to its varying nature, PsA has been classified into five subgroups:

1. Asymmetrical oligoarticular
This form accounts for approximately 70% of cases. It is the least severe form, affecting up to five joints of one side of the body. Asymmetric arthritis causes swelling and inflammation in the fingers or toes which can cause them to resemble sausages. This effect is known as dactylitis.2

2. Symmetrical polyarthritis
This form accounts for 15% of cases of PsA and resembles rheumatoid arthritis. It usually affects several joints (poly) and occurs in the same joints on both sides of the body (symmetrical) - the joints can be large or small.2

3. Distal interphalangeal joint predomination (DIP)
This form occurs in approximately 5% of people with psoriatic arthritis. It affects the small joints in the fingers and toes, closest to the nails (distal joints) and is associated with the nails changing appearance.2

4. Spondylitic
This form of psoriatic arthritis can cause inflammation of the spine as well as stiffness and inflammation in the neck, lower back or sacroiliac joints. Other joints, such as the hips, hands and feet can also be affected. This type of PsA occurs in about 5% of people with the condition.2

5. Arthritis mutilans
This form accounts for about 5% of cases of PsA. It affects the small joints of the hands and feet but can also affect the spine. It is a severe form of PsA and can be very destructive causing marked deformity of the joints.2

How is psoriatic arthritis diagnosed?

There are no specific diagnostic tests to detect psoriatic arthritis. Usually a series of examinations will be conducted by physicians to determine if the disease is present. Physicians will also investigate the patient’s family history. Due to the change in appearance of the finger and toe nails associated with PsA, these signs will also be assessed in combination with X-rays to detect changes in bones and joints. Blood tests will also be conducted to rule out other forms of arthritis. However there are no blood tests that specifically detect PsA.2,5

Is psoriatic arthritis treatable?

Whilst a number of treatments exist to help patients manage PsA, no cure exists for the disease. Treatment will also vary depending on the subtype and severity of the disease. The main goal of treatment for psoriatic arthritis aim to:5

· Reduce joint pain and swelling

· Control patches of psoriasis on the skin

· Reduce the progression of joint damage


Types of treatment

Therapeutic agents can be used alone or in combination with topical agents and in some cases Light treatment to help manage either symptoms of psoriasis or arthritis. The extent of each will depend on the level of severity and stage of the disease:3,5

· Topical and oral therapy5
These agents tend to be the first-line of treatment for psoriasis and are the most frequently used. Oral corticosteroids can help to manage widespread joint inflammation.

· Phototherapy5
For moderate psoriasis, physicians may recommend ultraviolet light +/- sensitising medication which is effective for treating psoriasis but are used with caution due to premature skin ageing and the risk of skin cancer.

· Non-steroidal Anti-inflammatory Drugs (NSAIDS)5
These can help reduce joint pain and swelling. They can be administered over a period of days, weeks or longer depending on the level of disease progression.

· Disease-modifying antirheumatic drugs (DMARDs)5
DMARDs are administered when response to NSAIDs are ineffective. They are used to reduce the progression of chronic forms of psoriatic arthritis and are more effective if administered before extensive damage of the disease has occurred.

· Biological Agents6
In active and progressive cases of PsA, NICE recommends the use of a number of TNFα inhibitors. These agents target specific molecules which are thought to be important in PsA disease progression.

References

1. Helliwell P S. & Taylor W J. Classification and diagnostic criteria for psoriatic arthritis. Ann Rheum Dis 2005;64(Suppl II):ii3–ii8.

2. Psoriasis Association UK. Psoriatic Arthritis https://www.psoriasis-association.org.uk/pages/view/about-psoriasis/treatments-for-psoriatic-arthritis (accessed June 2012)

3. Friberg C. Genetic studies of psoriasis and psoriatic arthritis. The Sahlgrenska Academy at Göteborg University Göteborg, Sweden 2007

4. National Institute of Clinical Excellence http://www.nice.org.uk/nicemedia/live/11966/40595/40595.pdf (accessed June 2012)

5. Arthritis Foundation http://www.arthritis.org/disease-center.php?disease_id=21 (accessed June 2012)

6. National Institute of Clinical Excellence

http://www.nice.org.uk/usingguidance/commissioningguides/biologicaltherapies/home.jsp#fig1 (last accessed October 2012)


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