10 Most Important Take Home Points: Psoriatic Arthritis

Arthur Kavanaugh, MD

Dr Kavanaugh, a renowned Rheumatologist, provides the ten most important take home points in psoriatic arthritis to help practicing dermatologists…

  1. Psoriatic Arthritis (PsA) is common, occurring in about 20-30% of patients who have skin psoriasis. Patients almost always have psoriasis before developing PsA, sometimes by a decade or more. At present, we are unable to predict which psoriasis patients will go on to develop PsA.
  2. PsA is under-recognized, under-diagnosed and under treated. With more treatment options available, it is likely more PsA patients will be seen in the clinic and we will have more options for treating them.
  3. There is no single screening test or set of questions for determining which psoriasis patients have PsA. Sometimes it is hard for rheumatologists to tell. It is hardest for people with less abundant joint involvement (oligoarticular), and hardest to differentiate PsA from osteoarthritis (which can be inflammatory). Highly sensitive imaging techniques such as musculoskeletal ultrasound are sometime used.
  4.  Important areas of potential involvement for PsA, in addition to the skin and nails, include: 1) peripheral joints (e.g. small joints of the hands and feet,  of the wrists and ankles, the  knees, etc); 2) spine arthritis (essentially ankylosing spondylitis [AS] in a PsA patient),  3) enthesitis (inflammation of the insertion of tendons and ligaments into bone) and 4) dactylitis (swelling of an entire digit) Treatment depends upon the activity in these different areas.
  5. Greater understanding of the immunopathophysiology of PsA has led to the introduction of novel therapies, particularly TNF inhibitors . TNF inhibitors are the “go-to” biologic in PsA, and are sometimes used even before DMARDs.
  6. TNF inhibitors can be effective for all manifestations of PsA, although not all patients respond. Factors that affect response include obesity, which decreases the severity of disease as well as attenuates the response to treatment. Potentially tapering drugs, particularly biologics, is an area of increasing interest in rheumatology.
  7. Biosimilar TNF inhibitors have been approved in several countries worldwide, and a biosimilar infliximab received a favorable review from the European Medicinal Agency (EMA) and is almost certain to be introduced in European countries this year. Although the biosimilar was studies in RA and AS, it is likely to receive the full approval that the originator infliximab has, including psoriasis and PsA.
  8. Switching of TNF inhibitors can be effective in PsA. Many rheumatologists believe, although it is not proven, that TNF inhibitors and methotrexate offer synergistic benefit in PsA.
  9. Newer therapies for diseases like PsA, such as IL-12/23 inhibitors and IL-17 inhibitors, have been effective for some patients and are helping to define a novel approach to autoimmunity. Different than for the TNF inhibitors, autoimmune diseases seem to have varied responses to these other specific agents.
  10. Other new agents for PsA include oral inhibitors such as apremilast (a PDE4 inhibitor). The seemingly very good safety profile of apremilast has attracted particular attention.