Psoriatic Arthritis: Causes, Symptoms and Treatment

Psoriatic arthritis (PsA) is a chronic inflammatory condition that affects the joints and is often associated with psoriasis, a skin disease characterized by red, scaly patches. This form of arthritis can lead to joint damage if left untreated, causing pain, stiffness, and swelling in various parts of the body. Despite being a common complication among people with psoriasis, psoriatic arthritis often goes unrecognized in its early stages, leading to delayed diagnosis and management. This article explores the causes, early signs, differences from rheumatoid arthritis, prevention strategies, and treatment options with a focus on Arava (leflunomide).

What Causes Psoriatic Arthritis?

The exact cause of psoriatic arthritis remains unclear, but it is generally considered a multifactorial disease, influenced by a combination of genetic, immune, and environmental factors. One of the most significant risk factors is having a family history of psoriasis or psoriatic arthritis. Studies show that up to 40% of individuals with PsA have a close relative with the same condition, suggesting a strong genetic predisposition. Specific genes related to immune system function, such as HLA-B27, have been linked to an increased risk of developing PsA.

The immune system plays a central role in the development of psoriatic arthritis. In PsA, the immune system mistakenly attacks healthy tissues in the joints and skin, leading to chronic inflammation. This autoimmune response causes the characteristic joint pain, swelling, and stiffness associated with the disease.

Environmental triggers can also contribute to the onset of psoriatic arthritis in genetically predisposed individuals. Infections, physical trauma (known as the Koebner phenomenon), stress, and certain medications may trigger the disease. Additionally, lifestyle factors like obesity and smoking have been identified as risk factors, potentially worsening disease severity and progression.

What are the first red flags of psoriatic arthritis?

Recognizing the early signs of psoriatic arthritis is crucial for timely intervention and to prevent joint damage. PsA can develop gradually with mild symptoms or appear suddenly with severe inflammation. Importantly, not all individuals with psoriasis will develop PsA, but those who do often report symptoms that affect their quality of life even in the early stages.

One of the first red flags is joint pain accompanied by stiffness and swelling, particularly in the morning or after periods of inactivity. This stiffness usually lasts more than 30 minutes and improves with movement, which is a hallmark of inflammatory arthritis. Unlike mechanical joint pain, which worsens with activity, inflammatory pain often improves as the joints are used throughout the day.

Another early sign is dactylitis, or "sausage digits," where an entire finger or toe becomes swollen. This diffuse swelling differentiates PsA from other types of arthritis, such as rheumatoid arthritis, where joint swelling tends to be more localized.

Enthesitis, the inflammation of the sites where tendons and ligaments attach to bones, is another characteristic feature of psoriatic arthritis. Common sites include the Achilles tendon at the back of the heel or the plantar fascia on the bottom of the foot, leading to heel pain or discomfort in the sole.

Many patients experience nail changes, such as pitting (small dents on the nail surface), ridging, thickening, or separation of the nail from the nail bed. These symptoms are closely linked to PsA and often coincide with psoriasis-related skin changes.

Fatigue is a common but often overlooked symptom of psoriatic arthritis. The chronic inflammation underlying the disease can lead to significant physical exhaustion, even in the absence of severe joint pain.

What's the difference between rheumatoid arthritis and psoriatic arthritis?

Psoriatic arthritis and rheumatoid arthritis (RA) are both forms of inflammatory arthritis, but they differ in their causes, clinical features, and disease progression. Understanding these differences helps in accurate diagnosis and treatment planning.

One of the main distinctions lies in the pattern of joint involvement. Psoriatic arthritis often affects the joints asymmetrically, meaning it can affect joints on one side of the body more than the other. In contrast, rheumatoid arthritis typically presents with symmetrical joint involvement, where the same joints on both sides of the body are affected simultaneously.

PsA commonly involves the distal interphalangeal joints (the joints closest to the nails), whereas RA tends to affect the proximal interphalangeal joints (middle joints of the fingers) and the metacarpophalangeal joints (knuckles).

Another key feature of psoriatic arthritis is enthesitis and dactylitis, which are rare in RA. These symptoms contribute to the unique appearance of swollen, sausage-like fingers or toes seen in PsA.

Nail changes are more prominent in psoriatic arthritis and are considered a diagnostic clue. RA, on the other hand, does not typically cause nail abnormalities.

Laboratory tests can also help differentiate the two conditions. Most patients with rheumatoid arthritis test positive for rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibodies, while these markers are usually negative in psoriatic arthritis. However, PsA may be associated with the presence of HLA-B27, particularly in cases with axial involvement (affecting the spine and sacroiliac joints).

Radiographic differences are also notable. Joint damage in RA typically leads to bone erosion without new bone formation, while PsA may show both erosion and new bone growth, leading to joint fusion in severe cases.

Can You Prevent Psoriatic Arthritis?

While psoriatic arthritis cannot be entirely prevented, especially in individuals with a strong genetic predisposition, certain strategies can reduce the risk of developing the disease or slow its progression.

Managing psoriasis effectively is crucial since PsA often develops in patients with existing skin symptoms. Regular dermatological care, combined with treatments that control skin inflammation, may reduce the risk of joint involvement.

Lifestyle modifications play a significant role in prevention and disease management. Maintaining a healthy weight reduces the mechanical stress on joints and decreases systemic inflammation. Obesity is not only a risk factor for developing PsA but also associated with more severe disease and reduced response to treatment.

Avoiding smoking and limiting alcohol consumption are beneficial, as both are linked to increased inflammation and poorer outcomes in psoriatic arthritis.

Early recognition and treatment of joint symptoms in psoriasis patients can prevent irreversible joint damage. Regular screening for musculoskeletal symptoms in individuals with psoriasis helps in early detection. If you have psoriasis and develop joint pain, swelling, or stiffness, consult a healthcare professional promptly.

Treatment of Psoriatic Arthritis: Focus on Arava (Leflunomide)

The management of psoriatic arthritis aims to control inflammation, relieve symptoms, prevent joint damage, and improve quality of life. Treatment options include non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids, conventional disease-modifying antirheumatic drugs (DMARDs), biologics, and targeted synthetic DMARDs.

Arava (leflunomide) is a conventional DMARD commonly used to treat psoriatic arthritis, especially in cases where NSAIDs are insufficient and before escalating to biologic therapy. Leflunomide works by inhibiting an enzyme involved in the proliferation of immune cells, thereby reducing inflammation and slowing disease progression.

Clinical studies have shown that leflunomide effectively reduces joint pain, swelling, and stiffness in psoriatic arthritis. It also helps improve physical function and quality of life for many patients. Unlike biologic therapies, which target specific molecules in the immune system, leflunomide has a broader immunosuppressive effect.

Arava is usually prescribed in a loading dose followed by a daily maintenance dose. The medication can take several weeks to achieve its full therapeutic effect, so patience is required during the initial phase of treatment.

While effective, Arava is not without side effects. The most common include gastrointestinal symptoms like diarrhea, nausea, and abdominal pain. Some patients may experience elevated liver enzymes, so regular monitoring of liver function tests is necessary. Other potential side effects include hair thinning, high blood pressure, and immunosuppression, increasing the risk of infections.

Due to its teratogenic effects, Arava is contraindicated in pregnancy, and women of childbearing potential must use effective contraception during treatment. Men wishing to father children should also discuss the risks with their healthcare provider, as leflunomide can affect sperm.

In cases where rapid drug elimination is needed (for example, before planned pregnancy), a cholestyramine washout procedure can accelerate the removal of leflunomide from the body.

Combination therapy with other DMARDs or biologics may be considered in patients with severe disease or those who do not respond adequately to leflunomide alone. However, this approach requires careful monitoring to manage potential drug interactions and side effects.

Final Thoughts

Psoriatic arthritis is a complex, multifaceted disease that requires a comprehensive approach to diagnosis and management. Understanding the causes, early signs, and differences from other forms of arthritis like rheumatoid arthritis is essential for timely intervention. While psoriatic arthritis cannot be fully prevented, early detection and lifestyle modifications can reduce the risk and slow disease progression.

Treatment options continue to evolve, with medications like Arava offering effective relief for many patients. However, therapy must be individualized, considering the severity of the disease, patient preferences, and potential side effects. Regular follow-up with a rheumatologist ensures optimal disease control and helps prevent long-term joint damage.

Medically Reviewed by Dr. Mevan Nandaka Wijetunga, MD