Early treatment of psoriatic arthritis improves prognosis.

Psoriatic arthritis (PsA) is a chronic, autoimmune disease, affecting up to 1% of the adult population and up to 40% of those with psoriasis. There is no universally accepted definition or diagnostic criteria for the disease although the CASPAR classification of PsA is now the most widely used. PsA has a peak age of onset between 35 and 55 years with an equal gender distribution. Around 20% of patients develop PsA before psoriasis, often many years before skin or nail changes. Enthesitis, pain and tenderness at the insertion of any tendon onto the bone, is characteristic and screening for enthesitis should include palpation of the lateral epicondyle of the humerus, the medial condyle of the femur and the achilles tendon insertion. Diagnosis of PsA relies on a detailed history, particularly as many of the manifestations may be mild or transient, and therefore not reported by the patient. There may be a previous, current, or family history of psoriasis. There are no diagnostic blood tests for PsA. The presence of rheumatoid factor or anti-CCP antibodies does not preclude a diagnosis of PsA, but should prompt careful scrutiny of the diagnosis. X-rays of the hands and feet should be performed at baseline for all those with suspected inflammatory arthritis. Features of back pain that suggest an inflammatory cause, rather than a mechanical problem, include the presence of early morning stiffness and pain that is relieved by exercise and exacerbated by rest. Any patient with suspected inflammatory arthritis and a six-week history of painful, swollen joints should be referred for specialist assessment. Patients with PsA have a higher self-rated disease severity than those with psoriasis only and a 60% higher risk of premature mortality than the general population, their life expectancy is estimated to be approximately three years shorter. Aggressive treatment of early stage progressive PsA can substantially improve the long-term prognosis.