Evan L. Siegel, MD, FACR
Psoriatic arthritis and psoriasis
Psoriasis is a common skin condition that affects 1-2 percent of the population, causing chronic, well- defined, red, sometimes itchy patches on the skin, with a superimposed silvery scale. Approximately one third of patients with psoriasis will develop psoriatic arthritis, a painful disease that can affect the peripheral joints including the hands, feet, elbows shoulders and knees, and also the spine, tendons and hips.
On average, psoriatic arthritis generally occurs about 9 to 10 years after the onset of psoriasis. Often the diagnosis is delayed because patients with psoriasis are not aware that arthritis can develop as a result of their skin disease. Even some health care professionals are not aware of all the potential skeletal complications that can occur in patients with psoriasis. A delay in diagnosis is problematic because studies have shown that damage to the joints can occur in some patients when appropriate treatment is not started promptly.
How psoriatic arthritis differs from other forms of arthritis
Psoriatic arthritis is an autoimmune disorder, unlike osteoarthritis which develops primarily as a result of wear and tear on the joints. This means that, as with rheumatoid arthritis (RA), the immune system erroneously attacks the joints causing inflammation and damage. However, psoriatic arthritis falls into a group of disorders that is distinct from RA, known as the “seronegative sponyloarthropathies” or SPA, which share similar or overlapping features.
This group includes psoriatic arthritis, ankylosing spondylitis, arthritis associated with inflam- matory bowel disease such as ulcerative colitis or Crohn’s disease, and reactive arthritis (arthritis that occurs secondary to an infection such as food poisoning or venereal disease). These disorders share some genetic and clinical features, and may share some biologic characteristics that lead to their development.
The diagnosis of psoriatic arthritis is based on symptoms and findings in the musculoskeletal system of a patient with current or past psoriasis or a family history of psoriasis. Joint symptoms typically include swelling, redness and warmth of a few or many joints, often in an asymmetric fashion.
What is frequently different about psoriatic arthritis when compared to RA is prominent involvement of tendons and “entheses,” the area where a tendon or ligament attaches to
The spine can be involved in about 40 percent of patients, but it is rare for the spine to be the only area involved in psoriatic arthritis. Spine involvement is felt as inflammatory- type back pain. Inflammatory back pain is different than routine mechanical back pain in that it is insidious as opposed to abrupt in onset, and gets better with activity and worse with rest. Inflammatory back pain frequently awakens sufferers from sleep at night.
Once the diagnosis is made, a patient’s condition is characterized as mild, moderate or severe based on disease activity assessed in all five areas of involvement in psoriatic arthritis (PsA). These areas include: the severity of skin disease, arthritis, back pain/spine involvement, dactylitis and enthesitis.
Treatment may include non-medical interventions such as physical therapy and exercise. Weight loss is important for many patients with PsA, as increased weight has been shown to not only increase the risk of developing this disease, but also to decrease effectiveness of medicines.
Psoriatic arthritis can also increase risk of cardiovascular complications (hypertension, heart attack and stroke). Prescribed medications may include non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or naproxen), standard disease-modifying antirheumatic drugs (DMARDs) such as sulfasalazine, methotrexate and leflunamide) and biologic therapies such as Enbrel, Humira, Remicade, Cimzia, Simponi, Stellara and Otezla.
Biologic agents are medications that interfere with biologic activity in the body that promotes ongoing inflammation. These agents help with the symptoms of both psoriasis and arthritis and some may help stop progression of the disease. The possibility of serious side effects exists with these and all medications, and should be discussed carefully with a rheumatologist to fully understand the risks and benefits before starting any new therapy. New biologic agents are also in clinical trials and will be available for general use for psoriatic arthritis in the near future.
Psoriatic arthritis is a potentially progressive disorder that not only can affect skin, joints, tendons and spine, but also can increase the risk of heart attack and stroke. Early recognition of this condition that allows appropriate treatment to begin is essential for relieving ongoing symptoms and possibly preventing future damage and disability.
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