Practical Considerations in Psoriatic Arthritis
MARCH 22, 2017
MD Magazine Staff
Allan Gibofsky, MD: I wish it were possible to reverse disease in patients with psoriatic arthritis. Unfortunately, there’s no good evidence that we do. However, we are able to significantly slow down the course of progression of the disease and provide patients with an enhanced quality of life, as well as improve their activities of daily living. TNF (tumor necrosis factor) inhibitors have really been a class of agents that have improved the lives of our patients with psoriatic arthritis, significantly. Often, you become unaware that the patients are affected by the disease because of how well they work and how well they cause significant improvement.
The decision whether to use, or not use, a TNF inhibitor, is based on the clinical evaluation of disease activity. There are 2 main disease activities that we measure—the activity in the skin and the activity in the joints—because psoriatic arthritis is, as I’ve indicated, an inflammatory condition of the joints in patients who have an inflammatory condition of the skin. Therefore, there are 2 disease measures. The first is of the skin, called the PASI (Psoriasis Area and Severity Index), and the second is of the joints. When measuring disease activity in the joints, there is no specific validated measure just for psoriatic arthritis. So we tend to borrow measures from rheumatoid arthritis and also tend to use measures that are reflective of where in the body the psoriatic arthritis is. If we’re talking about peripheral disease, for example, we may use the clinical disease activity index borrowed from rheumatoid arthritis, in which we sum up tender joints, swollen joints, the patient’s global assessment of their disease, and the physician’s global assessment of disease. And that gives us an objective validated metric at that point in time.
In addition, we may borrow from other diseases as well, if the patient has other forms of psoriatic arthritis. For example, if the patient has axial disease, meaning disease of their spine, we may borrow a measure from the ankylosing spondylitis world, something called the BASDAI (Bath Ankylosing Spondylitis Disease Activity Index), which measures things like activity of the disease as a result of impairment on bending and activity of the disease as a result of impairment of other measures and activities as well. So, we measure disease activities with objective metrics.
What do we aim for? We would like to get patients into remission, and that is often more difficult with psoriatic arthritis than it is with rheumatoid arthritis. Failing that, we want to get patients to the lowest disease activity score possible, because, again, we have taken a page from the rheumatoid arthritis literature showing that the better the control of disease, the lower the disease activity that your therapeutic efforts reach and the better the outcome in patients over time. There is a recent interesting study called TICOPA, which demonstrates that getting patients with psoriatic arthritis under tight control improves the outcome almost like getting a patient with diabetes under tight control and very much like getting a patient with rheumatoid arthritis under tight or aggressive control. Indeed, we’ve also borrowed a paradigm from rheumatoid arthritis called “treat to target.” And we are learning that by assessing our patients with psoriatic arthritis (both the skin and joints) during every visit and by tailoring our therapeutic efforts accordingly by aiming for either remission or low disease activity, rather than just simple symptom control, we can effectively modify the long-term outcome and improve the patient’s prognosis significantly.
Transcript edited for clarity.