Psoriatic arthritis (PsA) is a chronic inflammatory arthritis of the skin or nail psoriasis.It includes a set of heterogeneous arthritis, ranging from peripherally symmetrical polyarthritis, sometimes no difference clinically from rheumatoid arthritis (RA), to asymmetrically less arthritis, mostly lower extremities, axial spondylitis and epididymis and dactylitis.The latter clinical presentation explains the frequent classification of PsA in rheumatic diseases known as serous cervical spondylosis.
PsA affects an estimated six to seven people per 100,000 people in the United States each year.The prealence of PsA is about 0.04 to 0.1% of American adults.PsA occurs in 20-30%(range 6-42%) of psoriasis patients.The peak incidence occurs between 30 and 55 years of age and affects men and women equally.PsA usually occurs within seven years or simultaneously after the onset of psoriasis, although 15-20% of PsA patients are present before the onset of psoriasis.
The cause of
The exact cause of PsA is unknown, but genetic, infection and physical trauma are common underlying causes.Hla-b27, -b7, -b13, -b17, -b57, -cw *0602 and other major histocompatibility alleles were found to be related to PsA in the study of genetic susceptibility.Recently, a genome-wide association study (GWAS) of psoriasis and PsA patients found other susceptible sites, including IL23A, IL23R, IL12B, TNFAIP3, TNIP1, IL4, IL13 and TRAF3IP2.Group A streptococcus was associated with the development of guttate psoriasis, and ribosomal RNA of the bacterium was detected in the peripheral blood and synovial fluid of PsA patients.HIV is associated with psoriasis and PsA.Physical trauma, the so-called Koebner phenomenon, has been reported to cause the onset of psoriasis.
The severity of arthritis at PsA onset and subsequent course of disease may be related.Imaging evidence of joint erosion and poor response to initial drug therapy indicate more severe disease progression during acute phase of elevated reactants.In RA, PsA can significantly affect physical function and health-related quality of life.Joint damage can occur quickly if there is no immediate treatment intervention.
Other factors associated with poor prognosis include extensive skin involvement, younger age of onset, and a family history of psoriasis.
Psoriatic arthritis is also an autoimmune disease that can manifest as skin inflammatory psoriasis.Like rheumatoid arthritis, the disease attacks and damages joints, affecting the patient’s quality of life.Unfortunately, psoriatic arthritis is not well recognized in the general medical community, causing irreversible joint damage in many patients before diagnosis.However, the prognosis of psoriatic arthritis patients is improving due to new treatments and treatment plans.