While it is true that these two arthritis conditions may occur in the same person, there are several differences between these two autoimmune diseases. Psoriatic arthritis (PsA) is a chronic inflammatory disease of the joints. It occurs in up to 40% of patients who already have psoriasis.
One diagnostic that makes it different from rheumatoid arthritis is that the ‘rheumatoid factor’ in the serum is absent. The origin of the disease is still unclear but it has been found that a number of genetic factors play a significant role, in addition to environmental and other factors.
Individuals with Rheumatoid Arthritis (RA) and Psoriatic Arthritis (PsA) both suffer with similar erosive symptoms, such as pain, swelling, and stiffness, as well as fatigue from an overactive immune system. Both affect internal organs, as long term RA and PsA may lead to a weakening of the bones, called osteoporosis.
Both illnesses also can affect internal organs; long term progression of both RA and PsA may lead to inflammation, scarring, and damage to major internal organs, such as the lungs and heart. Both conditions may be treated with similar drugs; treatment of RA and PsA can be managed with anti-inflammatory medications (NSAIDS), corticosteroids, DMARDS (disease modifying anti-rheumatic agents) and finally surgery as a last resort to stabilize affected joints in the most serious cases.
Although many similarities exist between the two conditions, there are significant differences between them.
PsA often affects joints closest to the nail bed, meaning joints in the fingers and toes and the lower back. RA, however, affects a different set of joints, such as the middle of the fingers or toes, as well as the wrist. Individuals with RA will likely have an antibody present in their blood called rheumatoid factor, while patients with PsA do not have this antibody. Conversely, patients with PsA seem to have a genetic susceptibility to psoriatic disease, in addition to environmental factors, such as physical trauma and viruses that apparently trigger the abnormal immune response that is characteristic of PsA. RA is a symmetrical disease, meaning that the symptoms occur on both sides of the body.
Psoriatic Arthritis can be difficult and challenging, with significant stiffness, pain and sometimes, loss of function in affected joints. RA is similarly difficult, with both conditions causing significant pain. Yet some physicians fail to recognize that these two conditions are distinctly different diseases. Once one looks at the entire clinical, anatomical, microscopic and molecular levels, it is clear that RA and PsA are distinctly different diseases.
The end joints of the fingers are especially affected in PsA, but not in RA. Another difference is the involvement of the axial spine in PsA, most commonly the sacroiliac joints and the lumbosacral spine. But most telling are the molecular diagnosis tests, which have recently shown the differences between RA and PsA. Those molecular differences are beyond the scope of this report. The diagnosis is best conducted by your primary care physician, who may refer you to a rheumatologist for further testing.
Both RA and PsA are treated with a number of similar anti-inflammatory pharmaceuticals, as noted above. Several new pharmaceuticals are on the market with good results, including corticosteroids, TNF inhibitors, and the biological drugs that include Abatacept, Rituximab and Tocilzumab.
Talk to your doctor today if you have joint pain. You may benefit from early diagnosis and treatment.