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This supplement is the first collaborative publication of members of the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA). Many of the articles are based on presentations given at the first GRAPPA meeting in August 2003, as well as at subsequent GRAPPA meetings. We thank all the contributors for a job well done. We believe that these articles highlight current key findings and review key research issues in the field of psoriasis and psoriatic arthritis (PsA) and will serve as a background for future research.
The supplement began with the difficulties in classification of PsA. Despite these difficulties, there is light at the end of the tunnel—classification criteria are currently being derived from an international collaborative effort chaired by Philip Helliwell of Leeds, England. An important point for discussion is whether PsA should be approached as a unique identity or whether it should be lumped together with other members of the spondyloarthropathy group and assessed in the same manner. There is increasing support to view this condition as unique and separate from both rheumatoid arthritis and ankylosing spondylitis, at least in the clinical trial setting.
The clinical features of PsA as well as psoriasis have been described, with emphasis on the severity of the disease, as well as its effect on quality of life. Notably, patients recruited for clinical trials are similar to those recorded in longitudinal studies, and thus are representative of the disease, although likely to be more acutely active at the time of recruitment into trials.
The immunopathology of both skin and joint aspects of the disease have been depicted. There are similarities and differences, and further work is required to identify all pathogenic mechanisms. The successful use of antitumour necrosis factor (anti-TNF) agents and other emerging biological therapies have provided new insights into the pathogenesis of psoriasis and PsA. An exciting development in the past few years has been the successful treatment of both psoriasis and PsA with anti-TNF agents, which are effective for both skin and joint manifestations.
Patient advocacy groups have formed for psoriasis and PsA. They have raised awareness of these conditions and will likely play a major role in the future, particularly with emphasis on early diagnosis, treatment, and availability of newer medications to all who require them.
An important area is the development of assessment tools specific for PsA. These include both clinical assessment and imaging techniques. With the advent of new therapeutic modalities, there is a need for specific assessment tools that can be used across trials, as well as measure therapeutic response in clinical trials. The ethics of performing clinical trials, as well as the use of placebo medications, are at the forefront as we appreciate the severity and rapidity of progression of damage that can occur in PsA. Specific assessments tools are being developed for the assessment of patients with PsA. Members of GRAPPA have now identified domains to be included in clinical trials. This effort has been accepted by Outcome Measures in Rheumatology (OMERACT). The next important task will be to identify instruments to measure these domains, which will be valid, reproducible, sensitive to change over time, and feasible to perform in the course of clinical trials and evaluations in clinical settings.
This has been a major effort of a large group of people with a past and continued interest in psoriatic arthritis and psoriasis. This supplement has identified a number of areas requiring further study. Indeed, a research agenda has been generated both through the initial GRAPPA exercise and through the OMERACT 7 workshop on psoriatic arthritis (May 2004, Asilomar). Several committees of GRAPPA have been formed as a follow up of the research agenda. These are listed in table 1.
Our hope is that as these committees perform their activities and address the research agenda, current therapies will be more fully utilised and further therapies will be developed, which will make life better for patients with both psoriasis and psoriatic arthritis.