Will all psoriasis develop into psoriatic arthritis? Will it cause disability?

Author: Su Yin, Chief Physician, Peking University People's Hospital

Reviewer: Zhang Zhuoli, Chief Physician, Peking University First Hospital

Psoriatic arthritis, also known as arthritis psoriasis, is a chronic bone and muscle disease related to psoriasis. It is an autoimmune disease and can also be called a special type of psoriasis. It is mainly manifested by varying degrees of pain, swelling and deformation in peripheral joints and axial joints, which seriously affects the quality of life of patients.

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The cause and pathogenesis of psoriatic arthritis are unclear. Studies have found that genetic factors account for a large proportion, even higher than the genetic correlation of rheumatoid arthritis and ankylosing spondylitis, but it is not a genetic disease, but an autoimmune dysfunction caused by the combined effects of multiple genes, environmental factors, and infection.

Will all psoriasis develop into psoriatic arthritis? Psoriasis and psoriatic arthritis are closely related, but not all psoriasis will develop into psoriatic arthritis. The incidence of psoriatic arthritis in psoriasis patients is about 7%-35%, which means that 7%-35% of psoriasis patients may develop psoriatic arthritis.

The incidence of psoriatic arthritis is generally higher in middle-aged people, and slightly lower in the elderly. In addition, psoriasis patients with the following characteristics are prone to developing psoriatic arthritis: scalp psoriasis; rash in skin folds such as the navel and around the anus; severe rash that is difficult to control; nail changes such as thimble-like changes, nail subluxation, and nail whitening; and other concomitant diseases such as diabetes, hyperlipidemia, hypertension, and obesity. By understanding these characteristics, we hope to be able to identify which psoriasis patients are likely to develop psoriatic arthritis early, give active treatment and control, and prevent the disease from developing.

Psoriatic arthritis is mainly divided into five types, the most common of which are polyarthritis or oligoarthritis, each accounting for about 30%-40%. The large joints that are easily affected are generally peripheral joints, such as knee joints, ankle joints, and hand joints. The hand joints often involve the interphalangeal joints.

The polyarthritis type generally affects more than four joints; the spinal (axial) arthritis type mainly affects the spine; the mutilating arthritis type, also called the multi-joint involvement type, can cause rapid destruction of multiple joints, and joint deformities and joint destruction can occur in the early stages. This type is more serious; the distal interphalangeal (toe) arthritis type mainly affects the joints at the fingertips and is often accompanied by nail changes.

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These five types may not necessarily occur alone, but may occur together. For example, after the spinal joints are affected, the peripheral small joints may also be affected, and the distal interphalangeal (toe) joints may also be affected. It is also possible that the early stage is monoarthritis, and as the disease progresses, it progresses to polyarthritis, or it may progress to mutilating arthritis.

Psoriatic arthritis is characterized by joint pain and swelling. Some patients experience tenderness or pain around the joints, especially at the attachment points of the tendons where the muscles connect to the bones, such as pain in the heels or soles of the feet when walking.

Untreated peripheral arthritis, distal interphalangeal (toe) arthritis, and mutilating arthritis can lead to various deformities, such as shortened fingers, buttonhole deformities, and various joint dislocations. If it occurs in the spinal joints, it will cause the spinal joints to be unable to move, bend, or twist; if it affects the knee joints, the knee joints cannot bend, which affects walking; if it affects the foot joints, they cannot bear weight. The disability rate of psoriatic arthritis within 3-5 years is 75%.

The main purpose of treating psoriatic arthritis is to control the disease in its early stages and avoid joint deformities. If treatment is delayed and the bones are already damaged, medication can only delay or prevent further bone destruction, but the damage already done may not be repaired by medication. Unless surgery is performed, the damaged joints will be difficult to recover. Therefore, psoriatic arthritis requires active treatment.

The treatment of psoriatic arthritis mainly relies on drugs, including nonsteroidal anti-inflammatory drugs, traditional synthetic disease-modifying antirheumatic drugs and targeted drugs. Non-drug treatment mainly refers to functional exercise and physical therapy. Choose appropriate drug and non-drug treatment methods according to the specific condition.