Psoriatic arthritis is a progressive, multiform, chronic, immunological, inflammatory disease of joints and the whole organ system that is often familial and may lead to destruction of joints.
Starting treatment without delay may improve the patient's long term prognosis.
Treatment aims at reducing the systemic inflammation and at eliminating both skin and joint symptoms.
The patient should be motivated for treatment from the very beginning.
The treatment of psoriatic arthritis depends on the extent of symptoms, radiological progression, and the activity of the dermatological disease.
The treatment of psoriatic arthritis is based on methotrexate and good analgesia.
Biological treatment can be used, as necessary.
The risk of arterial disease, diabetes and potential depression associated with psoriatic arthritis should always be taken into account when planning the treatment.
Epidemiology
The prevalence of cutaneous psoriasis among the European and North-American population is 1.5-3%. In an unselected population, the prevalence of psoriatic arthritis is 0.05-0.25%.
At the onset of psoriasis, 2.4% of patients have psoriatic arthritis.
The risk of psoriatic arthritis increases with increasing duration of psoriasis, and 5-7% of patients with psoriasis also have arthritis.
In severe psoriasis, the risk of arthritis is 40-50%.
Psoriatic arthritis may occur without skin symptoms.
Psoriatic arthritis of small joints is equally common in men and women but the disease with spondylarthritis is more common in men.
The incidence of psoriatic arthritis has increased during the last few decades.
People with psoriasis and psoriatic arthritis have many associated disorders, such as cardiovascular disorders, diabetes, IBD and depression. Particular attention should be paid to their treatment.
History, symptoms and findings
Susceptibility to the disease is determined by genetic factors.
Patients often have a family history of psoriasis.
Psoriatic arthritis as such is not clearly associated with HLA-B27 positivity.
Psoriatic arthritis should be suspected if a patient with cutaneous psoriasis develops symptoms of arthritis and clinical findings consistent with psoriatic arthritis.
However, cutaneous psoriasis does not exclude diseases such as rheumatoid arthritis Rheumatoid Arthritis.
Clinical findings typical for psoriatic arthritis
Joint symptoms are multiform and often asymmetric.
Painful joints and tenderness and inflammation of tendon insertions (enthesitis), such as inflammation in the heel bone at the insertion site of the Achilles tendon commonly occur.
Asymmetric inflammation of a few joints is the most common manifestation.
Polyarthritis
May at first clinically resemble rheumatoid arthritis.
Both rheumatoid factor (RF) and serum citrullinated peptide antibodies are usually negative.
Inflammation of DIP joints (often PIP + DIP), often associated with typical nail changes ( 123). It may be very painful.
Dactylitis (sausage finger or toe)
Asymmetric sacroiliitis and spondylitis are common in patients with spondylarthritis.
Typically callus formation on bone surfaces, i.e. in the periosteum
Polyarthritic disease eroding bone, and a form of disease causing swelling of the whole limb are rare.
Uveitis can be seen in patients with psoriatic arthritis.
Diagnosis
The diagnosis is clinical; there are no exact diagnostic criteria.
The diagnostic criteria of the CASPAR working group can be used to define the disease. However, it should be remembered that they were made for use in research.
Psoriatic arthritis cannot be diagnosed based on laboratory tests.
Patients with psoriatic arthritis may have elevated plasma urate levels in the absence of gout.
ESR and CRP may be either elevated or normal.
Rheumatoid factor and anti-CCP antibodies may be exceptionally elevated.
Changes possibly seen in X-ray can be used for diagnosis.
Periosteal callus formation
Bone erosion
Complete fusion of joints
'Pencil-in-cup' changes in small phalangeal joints
Unilateral sacroiliitis
Asymmetric bulky syndesmophytes, 'jug handles', between vertebrae
In the mutilating form of the disease, the middle phalanx, for example, may dissolve completely.
Changes in X-rays may appear early.
Articular ultrasonography will show thickened synovial membranes with increased blood flow, increased amounts of synovial fluid, increased blood flow in the periosteum, callus formation, erosions and tendonitis.
Magnetic resonance imaging (MRI) can be used to confirm vertebral and sacroiliac (SI) joint inflammation before changes can be seen in conventional X-ray. MRI is important also in the assessment of the inflammation and changes in large joints, such as the hip joints. The need for MRI will be defined by a specialist.
Treatment depends on assessment by patient and doctor, the number of inflamed joints, radiological progress and degree of disease of the skin.
If, however, there are several symptomatic joints or the disease is progressive, methotrexate, or if it is contraindicated sulphasalazine, is used already at an early stage.
A mild psoriatic arthritis is treated with NSAIDs and local intra-articular glucocorticoid injections.
If local glucorticoid injections do not suppress the arthritis adequately, the first-line therapy is methotrexate.
General remarks
Anti-inflammatory analgesics are used particularly in the beginning of the disease; for the form of disease with spondylarthritis and enthesitis, treatment may be needed for several years.
Methotrexate is the primary sDMARD for psoriatic arthritis. If methotrexate is contraindicated, sulfasalazine is chosen. Methotrexate often also alleviates cutaneous symptoms.
Sudden withdrawal of high-dose systemic glucocorticoids may aggravate cutaneous psoriasis.
Ciclosporin is may be effective in the treatment of both skin and joint symptoms, but is is not suitable for long-term treatment.
Intra-articular glucocorticoid injections are usually effective.
Biological drugs (bDMARD) alleviate both skin and joint inflammation.
According to clinical experience, the prognosis of psoriatic arthritis is often better than that of rheumatoid arthritis, and treatment started without delay may predict a milder clinical course.
Treatment chain
Patients, whose joint disease is stable, are usually followed-up within primary health care. Also the screening and treatment of associated diseases can be carried out in primary health care.
In active and progressive disease, the treatment of psoriatic arthritis is often carried out in cooperation by primary health care, a dermatologist and a rheumatologist.
Without consulting a specialist, a physician in primary health care may provide symptomatic treatment and intra-articular glucocorticoid injections for mild psoriatic arthritis.
Mild disease usually causes joint pain or rarely inflammation of individual joints.
Patients to be referred for an assessment by a rheumatologist include those with fresh polyarthritis (inflammation of more than 4 joints), with a disease that resembles ankylosing spondylitis or with a prolonged inflammation of a few (less than 4) joints that responds poorly to NSAIDs and local glucocorticoid injections or when X-rays show progressive changes.
Later on, treatment can usually be provided either entirely in primary health care or the responsibility shared with specialized care.
Severe forms of disease are treated in specialized care.
Children with psoriatic arthritis should be treated in specialized care.
Before pregnancy, a safe pharmacotherapy to be used during pregnacy should be planned and, as required, a rheumatologist consulted.
Follow-up
Results of treatment should be followed up and assessed regularly.
Full care of the patients should include screening and careful treatment of diseases associated with psoriasis.
The medication needs to be monitored by safety tests. See locally available guidance.
The special features of biological medicines (bDMARD) should be kept in mind in primary health care, too.
Measurement tools are available for following up and assessing response to treatment.
In the peripheral form of disease, response to treatment can be assessed using indicators used for the follow-up and assessment of response to treatment in patients with rheumatoid arthritis (DAS28, ACR response, HAQ, VAS)
The form of disease with spondylarthritis can be monitored using indicators of response to the treatment of ankylosing spondylitis (BASFI, BASDAI, VAS).
In patients with enthesitis, response to treatment can be assessed using VAS and MASES indicators.
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