psoriatic arthritis

psoriatic arthritis
Name	Psoriatic arthritis
Field	Rheumatology, Dermatology

psoriatic arthritis. It is a chronic, inflammatory arthritis that occurs in individuals with the skin condition psoriasis. The disease is classified as a type of spondyloarthritis and can lead to significant joint damage and disability if not managed appropriately. Its presentation is highly variable, affecting peripheral joints, the axial skeleton, and entheses.

Signs and symptoms

Clinical manifestations are diverse, often involving joint pain, stiffness, and swelling. Peripheral arthritis can be asymmetric or symmetric, and may present as dactylitis, causing entire digits to swell, or as arthritis mutilans, a severe, deforming subtype. Axial disease involves inflammation of the sacroiliac joint and spine, similar to ankylosing spondylitis. Enthesitis, inflammation at sites like the Achilles tendon or plantar fascia, is common. Skin findings of psoriasis, such as plaques or nail psoriasis with pitting and onycholysis, typically precede joint symptoms, though arthritis can occur first. Extra-articular features may include uveitis and inflammatory bowel disease.

Causes and risk factors

The exact etiology is unknown but involves a complex interplay of genetic, immunological, and environmental factors. A strong genetic association exists with the HLA-B27 allele, particularly in axial disease, and other genes in the major histocompatibility complex like HLA-C*06:02. Dysregulation of the immune system, involving cytokines such as tumor necrosis factor-alpha, interleukin-17, and interleukin-23, drives inflammation. Environmental triggers like physical trauma or infection may initiate disease in genetically predisposed individuals. The primary risk factor is a personal or family history of psoriasis.

Diagnosis

Diagnosis is clinical, based on history and physical examination, as there is no single definitive test. Classification criteria, such as the CASPAR criteria, are used in research and require evidence of psoriasis plus features like dactylitis, nail changes, a negative rheumatoid factor, or new bone formation on imaging. Imaging studies like radiography, magnetic resonance imaging, and ultrasonography can detect erosions, joint space narrowing, and enthesitis. Laboratory tests are mainly to rule out other conditions like rheumatoid arthritis or gout; C-reactive protein may be elevated.

Treatment

Management aims to control symptoms, prevent structural damage, and improve quality of life. First-line therapy often includes nonsteroidal anti-inflammatory drugs and intra-articular corticosteroid injections. Conventional disease-modifying antirheumatic drugs like methotrexate, leflunomide, or sulfasalazine are used for persistent peripheral arthritis. For inadequate response, targeted therapies are employed, including tumor necrosis factor inhibitors like adalimumab and etanercept, interleukin-17 inhibitors like secukinumab, interleukin-12/23 inhibitors like ustekinumab, and Janus kinase inhibitors like tofacitinib. Physical therapy and surgery, such as arthroplasty, may be necessary for advanced disease.

Prognosis

The disease course is heterogeneous, ranging from mild, intermittent symptoms to severe, progressive joint destruction. Early diagnosis and aggressive treatment improve long-term outcomes. Poor prognostic factors include polyarticular involvement, elevated acute-phase reactants, radiographic damage at presentation, and functional limitation. Complications can include severe disability from arthritis mutilans, cardiovascular disease associated with systemic inflammation, and visual impairment from uveitis. With modern therapies, many patients achieve remission or low disease activity.

Epidemiology

It affects an estimated 0.1% to 0.25% of the general population, and up to 30% of patients with psoriasis will develop the condition. Onset typically occurs between ages 30 and 50, affecting men and women equally, though axial disease may be more common in men. The prevalence varies geographically and among different ethnic groups. Its incidence appears to be increasing, possibly due to better recognition and the rising prevalence of psoriasis.

Category:Autoimmune diseases Category:Arthritis Category:Rheumatology