OVERVIEW

What is psoriatic arthritis?

Psoriasis is a complex, chronic inflammatory systemic disease caused by the interaction of genetic, immune, and environmental factors. Psoriatic arthritis is an inflammatory disease associated with psoriasis, often characterized by pain and stiffness in the affected joints.

Is psoriatic arthritis common?

The prevalence of psoriatic arthritis in the general population is approximately 0.1%, while among psoriasis patients, it ranges from 4% to 30%. However, prevalence rates vary significantly across different regions.

SYMPTOMS

What are the manifestations of psoriatic arthritis?

• The common clinical manifestations of psoriatic arthritis include joint pain, stiffness, and swelling. Half of the patients experience morning stiffness lasting more than 30 minutes. Stiffness worsens with prolonged immobility and improves with activity. About 70% of patients with arthritis have a history of psoriasis.
• During physical examination, affected joints exhibit stress pain, tenderness along the joint line, and effusion, often with an asymmetric distribution. Approximately 40%–50% of patients experience involvement of the distal interphalangeal joints (toes/fingers) and spinal involvement.
• Additionally, most patients with psoriatic arthritis first develop skin changes associated with psoriasis, often accompanied by nail abnormalities such as pitting or onycholysis. Some patients may also experience enthesitis, dactylitis (sausage digits), and tenosynovitis.

Which joints are commonly affected by psoriatic arthritis?

Psoriatic arthritis often involves distal joints such as the fingers/toes, typically in an asymmetric pattern. However, many patients also experience axial joint involvement, such as the spine, and the affected joints may sometimes be symmetrical.

What consequences can psoriatic arthritis cause?

Psoriatic arthritis leads to symptoms such as pain and stiffness in the affected joints. In severe cases, it can cause difficulties in hand and body movement, thereby impacting the patient's quality of life and social interactions.

CAUSES

What causes psoriatic arthritis?

The exact cause of psoriatic arthritis (PsA) and psoriasis remains unclear. Genetic, immune, and environmental factors are all involved, with some shared mechanisms likely playing a role in both conditions.

Among environmental factors, several have been linked to the development of psoriasis and PsA, including infections (bacterial and viral) and physical trauma.

Is psoriatic arthritis hereditary?

There is a genetic possibility. Current research indicates that genetic factors play a significant role in the pathogenesis of psoriasis and psoriatic arthritis, with multiple associated genes identified as contributors to the disease.

DIAGNOSIS

What tests are needed to diagnose psoriatic arthritis?

• First, a thorough physical examination of the patient's skin, nails, and suspected affected joints is required to check for psoriatic skin lesions, nail changes, joint tenderness, swelling, or deformities.
• Second, laboratory tests are needed, including C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), white blood cell count (WBC), rheumatoid factor (RF), anti-citrullinated peptide antibody (anti-CCP), and HLA-B27.
• Finally, imaging tests such as X-rays, CT scans, or MRI may be necessary.

Generally, if a patient presents with both psoriasis and inflammatory arthritis in a typical pattern of psoriatic arthritis (PsA), the diagnosis can usually be confirmed.

Why are these tests necessary for psoriatic arthritis?

• Physical examination: A comprehensive physical exam is key to diagnosis. Joint symptoms, psoriatic skin lesions, and nail changes are critical diagnostic criteria for PsA.
• Laboratory tests: These are often nonspecific but aid in diagnosis. Elevated CRP, ESR, and WBC indicate nonspecific inflammation. RF and anti-CCP are usually negative, helping differentiate PsA from rheumatoid arthritis. HLA-B27 testing can identify psoriasis patients at risk of developing PsA.
• Imaging tests: These often reveal characteristic findings, such as simultaneous erosive changes and new bone formation in the same joint or digit, terminal bone resorption, pencil-in-cup deformity, or coexisting joint destruction and ankylosis. MRI is more sensitive.

Which diseases are easily confused with psoriatic arthritis?

• Rheumatoid arthritis: Typically presents as symmetric polyarthritis, usually sparing axial joints like the spine. Patients lack psoriatic skin or nail changes, and RF and anti-CCP are often positive. In contrast, PsA is often asymmetric, may involve axial joints, and most patients have psoriasis, with RF and anti-CCP usually negative.
• Ankylosing spondylitis: A form of axial spondyloarthritis, it lacks psoriatic skin or nail changes, and imaging can easily distinguish it from PsA.

TREATMENT

Which department should I visit for psoriatic arthritis?

Dermatology or rheumatology.

How is psoriatic arthritis treated?

The goal of psoriatic arthritis treatment is to control inflammation and prevent discomfort, joint damage, and disability. It mainly includes drug therapy and non-drug therapy:

Non-drug therapy: Adequate rest, avoiding excessive fatigue and joint damage, joint function exercises, and patient education.

Drug therapy: Specific treatments vary depending on disease severity:

• For mild peripheral arthritis (defined as involvement of fewer than 4 joints, no radiographic damage, and minimal discomfort or functional impairment), initial treatment with nonsteroidal anti-inflammatory drugs (NSAIDs; e.g., naproxen or celecoxib) is recommended over disease-modifying antirheumatic drugs (DMARDs).
• For patients with persistent active peripheral arthritis after NSAID treatment, moderate-to-severe peripheral arthritis without erosive changes or severe functional limitations, or axial symptoms well-controlled by NSAIDs, traditional (small-molecule) DMARDs (e.g., methotrexate, MTX) are recommended over biologics. Methotrexate can also be replaced by leflunomide (LEF) or sulfasalazine (SSZ). SSZ may be tried in patients unable to use MTX or LEF.
• For severe disease with erosive changes and functional limitations, TNF inhibitors are recommended as first-line therapy over traditional non-biologic DMARDs. Other biologic DMARDs (e.g., secukinumab or ustekinumab) may also be alternatives to TNF inhibitors.
• For patients with no significant improvement in joint count or persistent tenderness/swelling in ≥3 joints after 3 months of traditional DMARDs (e.g., MTX), TNF inhibitors are recommended over trying other traditional DMARDs sequentially.
• For peripheral arthritis patients with inadequate response to initial TNF inhibitors, another TNF inhibitor may be used instead of switching to a different class of biologics. For example, switching from an antibody-based TNF inhibitor (e.g., infliximab, adalimumab, golimumab, certolizumab) to a soluble TNF receptor (etanercept), or vice versa.
• For mild axial disease (i.e., sacroiliac/spine involvement), including inflammatory back pain without functional impairment, NSAIDs at anti-inflammatory doses (e.g., naproxen, indomethacin, celecoxib) are recommended over biologics.
• For axial symptoms poorly controlled by NSAIDs (e.g., prolonged morning stiffness, severe pain interfering with function), TNF inhibitors are recommended over traditional non-biologic DMARDs, as the latter are ineffective for spondylitis.
• For axial symptoms with inadequate response to initial TNF inhibitors, another TNF inhibitor may be tried. If the response remains insufficient, switch to other biologics (e.g., secukinumab or ustekinumab).
• For enthesitis (commonly affecting Achilles tendon/plantar fascia) causing functional impairment unresponsive to NSAIDs/local therapy, biologics (initially TNF inhibitors) may be used.
• For dactylitis unresponsive to NSAIDs, traditional DMARDs (e.g., MTX) may help. If traditional DMARDs fail, biologics (e.g., TNF inhibitors) should be used.
• Oral glucocorticoids should be avoided in psoriatic arthritis. If necessary (e.g., for severe flares), use the lowest effective dose, as they may increase the risk of erythroderma or pustular psoriasis. Intra-articular glucocorticoid injections may sometimes be used, avoiding psoriatic plaques.

What are the potential adverse effects of psoriatic arthritis medications?

• NSAIDs can relieve joint pain/swelling but do not alter disease progression or prevent/slow joint damage. Side effects may include elevated blood pressure, blood sugar, and gastrointestinal irritation.
• Immunosuppressants may cause gastrointestinal irritation, liver/kidney toxicity, bone marrow suppression, and increased infection risk.
• Biologics may lead to dizziness, headaches, increased infection risk, injection-site reactions, or gastrointestinal irritation.

Can psoriatic arthritis be cured?

Most patients achieve remission with active treatment, and some may even achieve complete remission. However, recurrence is common in many cases.

DIET & LIFESTYLE

What should patients with psoriatic arthritis pay attention to in their diet?

Patients with psoriatic arthritis should try to quit smoking and drinking.

What should patients with psoriatic arthritis pay attention to in daily life?

• First, engage in appropriate exercise, physical therapy, and training;
• Second, maintain a healthy weight and avoid obesity;
• Third, prevent infections and seek prompt treatment if infections occur;
• Fourth, avoid any physical injuries.

PREVENTION

Can psoriatic arthritis be prevented? How to prevent it?

Psoriatic arthritis can be prevented to some extent, such as actively controlling weight, quitting smoking and limiting alcohol, avoiding infections and injuries, etc.

How can patients with psoriatic arthritis prevent serious complications?

Once symptoms appear, seek medical attention promptly, actively undergo treatment, and follow up regularly. Early-stage disease is relatively mild and can be significantly improved with proper treatment. Many patients with severe complications result from lack of treatment or incorrect, non-standard treatment, leading to prolonged illness.