Psoriasis Update 2011: Psoriatic Arthritis (PsA)

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Arthur Kavanaugh, MD

In this presentation, Dr Arthur Kavanaugh, of UCSD, discusses the newest concepts in the management and treatment of patients with psoriatic arthritis (PsA).

A major question still exists among healthcare professionals…Is methotrexate (MTX) effective among our PsA patients? Dr Kavanaugh states that in a room full of Rheumatologists, everyone would agree that MTX is effective; however, the data doesn’t necessarily indicate its effectiveness, as it is somewhat lacking.

For more information on the history and data around MTX, Dr Theodore Pincus recently published a study in Clinical and Experimental Rheumatology focusing on the use of MTX in various disease states, including skin disease and PsA.

There are very few studies utilizing MTX in psoriatic arthritis and little support for its use in PsA patients. There were a total of 4 double-blind, placebo-controlled randomized clinical trials in the published literature.

There is not a lot of support for MTX in patients with active PsA. A number of studies utilized higher doses of MTX; therefore, we can see a dose effect, (patients taking over 15mg/week of MTX) in patients with psoriatic arthritis, which shows that there is some benefit to its use.

The MIPA study, a 6-month, double-blind placebo-controlled trial, was based out of the UK. The entry criteria required one swollen joint. The researchers were able to recruit only 221 patients over the course of eight years.  There were lots of drop-outs and in conclusion the results were questionable as to the value of MTX in patients with active PsA. There are a few issues with this study and the researchers reported that healthcare providers need to see the full data and the question still remains:  is the 15mg dose of MTX really effective?

Dr Kavanaugh recently participated in a PsA panel that was organized through EULAR (European League Against Rheumatism), with the intent to develop guidelines for the management of PsA. The panel concluded that patients with active PsA should be on MTX before one would be given a biologic. This recommendation would be questionable to many US dermatologists, and, in turn, the EULAR panel did revise their statement to allow for patients in “exceptional” cases to be started on a biologic.  It is really up to the clinician and patient to decide on the appropriate therapy based upon the data, quality of life, benefits and risks.

Data do exist around the efficacy of TNF inhibitors plus MTX in Rheumatoid Arthritis patients; yet, the data are limited in patients with PsA.  A systematic review of the TNF inhibitors demonstrated a risk ratio response of about 11 for an ACR 50 and a risk ratio of 17 for a PASI 75.

Is there synergy when utilizing MTX plus a TNF inhibitor in PsA? It is known in Rheumatoid Arthritis patients, yet it is unknown among our PsA patients.

The RESPOND study compared MTX (15mg/week) to INF (5mg/kg)+ MTX (15mg/week) and showed that the patients in combination did better than those on MTX alone.

Assessing Psoriatic Arthritis

When assessing PsA, it is imperative that healthcare providers look at each patient individually. It is important to consider peripheral arthritis, and look at swollen joints and the composite scores; clinicians need to consider axial arthritis, quality of life, radiographs, skin disease and other issues such as dactylitis (swelling of the entire digit) and enthesitis.

The CPDAI (Clinical Psoriatic Disease Activity Index) is a new instrument for disease activity and various clinical domains of PsA. This has been borrowed from the GRAPPA group, and broken into its individual domains. When we have these tools, we can then begin discussing remission. It’s important to consider all of the different facets of this disease (skin, joints, spine dactylitis, etc…) The important thing to consider regarding patient management is that each patient has to be looked at individually, as it is not an algorithmic treatment/management strategy.