Arthritis and Psoriasis
Psoriasis is a common condition which is difficult to treat and the treatments for it can be less than pleasant for the patients. Patients may present with psoriasis and joint symptoms but the diagnosis of an arthritic syndrome connected with the skin condition is not always made. Psoriatic arthritis is a joint disorder with many aspects and untreated can cause significant and permanent joint damage, with associated disability and lowering of the quality of life. Psoriasis occurs in the United Kingdom at a prevalence of around two percent, with around fourteen percent of psoriasis sufferers having some symptoms of joint involvement.
The symptoms of joint involvement can be present in about 15 percent of people before any of the skin changes become obvious and ultrasound of tendons in people with psoriasis have shown abnormalities without any joint symptoms. A lesser number of joints are typically affected in psoriatic in comparison to rheumatoid arthritis although they may be affected in a similar arrangement, with in some instances only one or two joints affected. The entheses, the areas where the ligaments and tendons are attached to the bones, are typically affected with pain and inflammation. The attachment of the Achilles tendon to the heel bone is a good example.
With so many entheses in the body this might explain why some patients complain of widespread pain symptoms not be closely related to their joints. Individual joints of the fingers can swell, either on their own or with involvement of other joints, and this is a negative sign for the disease. Inflammatory back pain present with the typical features which also occur in ankylosing spondylitis. Usual symptoms are early morning stiffness, steady and gradual onset, worse pain at night, pain better with exercise and worse with resting. Back involvement may be present but not give symptoms in up to a third of patients. Inflammation of the end joints of the fingers and nail involvement may also occur.
As people get older they increasingly complain of joint problems so it is easy to miss the signs in a person with psoriasis. A clinician should always be suspicious of the possibility of psoriatic arthritis in any patient with psoriasis who presents with a musculoskeletal complain, particularly if it involves the end finger joints or they have back pain which appears inflammatory. The ESR (erythrocyte sedimentation rate) and the CRP (C-reactive protein) blood tests are routine investigations and both can be elevated in inflammatory conditions. If a joint condition is suspected and there are no signs of psoriasis it is wise to carefully check the person's body for hidden signs of psoriatic skin lesions to exclude this highly genetic condition.
Typically 30% of people diagnosed with this condition will suffer with non-progressive disease in a few affected joints. This presentation is usually effectively treated with steroid injections into the joints as required and by symptomatic management. Identifying this group initially is important to exclude those with worse disease who are likely to show increased inflammatory blood markers, to be male, to have a larger number of affected joints and to have used steroids previously. If showing these negative factors they are more likely to develop damaging disease to the joints with increased disability and a reduction in their quality of life.
Psoriatic arthritis sufferers have benefited less from research and development that those who have other major arthritic conditions but over the last ten years there has been a large increase in investigations concerning this disease. Development of the recent biological treatment agents has stimulated new treatment methods. Despite this there is still a lack of evidence for treatments and when to apply them.
A joint damaging and fast advancing arthritic disease is present in around 5% of sufferers from psoriatic arthritis. Cardiovascular disease and metabolic syndrome are more common and affect life expectancy so it is important to identify and control risks such as cholesterol, being overweight, hypertension and smoking. Patients should be referred to a rheumatologist if they have psoriasis and any features of joint problems, remembering that some patients present with pain which is widespread or conversely which is very local such a bilateral tennis elbow. Joint protection is best provided by early referral to prevent long term damage.