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ASessment in Ankylosing Spondylitis (ASAS) international working group: a model for psoriatic arthritis and psoriasis?
  1. D van der Heijde1,
  2. J Braun2,3,
  3. R Landewé1,
  4. J Davis4,
  5. J Sieper2,5,
  6. S van der Linden1,
  7. M Dougados6
  1. 1Department of Internal Medicine, Division of Rheumatology and Caphri Research Institute, University of Maastricht, the Netherlands
  2. 2Rheumazentrum Ruhrgebiet, Herne, Germany
  3. 3Medical Department I, Rheumatology, Benjamin Franklin Hospital, Free University Berlin, Germany
  4. 4Division of Rheumatology, University of California at San Francisco, San Francisco, USA
  5. 5German Rheumatism Research Center Berlin, Germany
  6. 6Department of Rheumatology, Hopital Cochin, University of Paris, France
  1. Correspondence to:
    D van der Heijde
    Department of Rheumatology, University Hospital Maastricht, PO Box 5800, 6202 AZ Maastricht, the Netherlands;

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The ASsessment in Ankylosing Spondylitis (ASAS) working group is an international assembly of experts in the field of ankylosing spondylitis (AS). The group consists of rheumatologists, clinical epidemiologists, and patients, with a multinational representation of participants. The mission of ASAS is to support and promote the study of AS. This includes:

  • increasing awareness and promoting early diagnosis of the disease

  • development and validation of assessment tools

  • evaluation of treatment modalities in order to promote clinical research with the ultimate goal to improve outcomes.

The major focus of ASAS, thus far, has been on outcome assessment including the development, validation, and standardisation of instruments.


ASAS began in 1995 as an informal group. However, during the ensuing years there was a growing interest in the field of AS and in the work done by ASAS. This necessitated a more formal structure. At present, ASAS consists of an executive steering committee, an advisory board, members, and corporate partners. The following persons form the steering committee: Désirée van der Heijde (president), Maxime Dougados (vice-president), Jochen Sieper (treasurer), John Davis (secretary), Jürgen Braun, and Sjef van der Linden. Persons with a dedicated interest in AS, as evident from past or present performance in clinical care, research, teaching, or the conduction of studies in the field of spondyloarthritides, can apply for membership. Members are expected to be active participants taking part in a workshop or in one of the questionnaires at least once every calender year. Meetings are organised in concurrence with the European League Against Rheumatism (EULAR) and American College of Rheumatology (ACR) annual meetings. In addition, there is one separate workshop per year, often in conjunction with the International Congress on Spondylarthropathies. ASAS has a website listing all the members (70 at the beginning of 2004), corporate partners, and activities of the group (


Any member can propose a project to the executive steering committee. This person will become the project leader for that particular project, and at least one of the members of the steering committee will be part of the project group. Projects processed in this way are labelled as “ASAS projects” and may eventually result in recommendations by ASAS for publication or promotion. Subjects for these projects are often taken from the research agenda, which is formulated at the end of every workshop. In principle, the recommendations are evidence based as far as possible. The Outcome Measures in Rheumatology (OMERACT) filter addressing truth, discrimination, and feasibility forms the basis for assessing various aspects of validity of instruments. Delphi exercises, questionnaires, nominal group discussions, plenary discussions, and voting are important techniques leading to final consensus and recommendations.


Core sets, response criteria, partial remission criteria

The first activity of the ASAS working group was the selection of core sets of instruments to be included in all studies assessing symptom modifying antirheumatic drugs (SMARDs) and studies assessing disease controlling antirheumatic therapy (DC-ART), and a core set for clinical record keeping. First, the domains to be included in each core set were selected.1 For this purpose, the ASAS working group considered the whole spectrum of spondyloarthritides and, especially, the main clinical presentations—that is, axial involvement, peripheral articular involvement, enthesitis, and extrarheumatological domains, such as eye, skin, and gut involvement. Later, the instruments for each domain were identified.2 For a few domains, no preferred instrument could be agreed upon. This resulted in research projects aimed at addressing this issue. When these data became available, the core sets were updated in a workshop after the presentation of the new data.

After the definition of the domains with the accompanying instruments, the presentation of results at an individual level was considered for each instrument and for the combinations of instruments evaluating different domains. Response criteria as well as partial remission criteria that permitted us to combine different domains and present the results at an individual level were defined.3 These criteria enabled us to define the presence or absence of a response and a good clinical condition (partial remission) on the patient level. Evaluation of the optimal cut-off of the different instruments permitted us to define the Minimal Clinical Important Improvement (MCII). An evaluation of the optimal cut-off of the Patient Acceptable Symptomatic State (PASS) is ongoing.

The advantage of the core sets and the response and partial remission criteria is the standardisation of outcome assessment. With the advent of new treatment modalities, such as the selective cyclo-oxygenase-2 inhibitors and antitumour necrosis factor (anti-TNF) agents, many trials in AS are anticipated. It is hoped that the use of the same core of outcomes will improve comparability of data.

Recommendations for conducting clinical trials

The ASAS working group, together with the Spondylitis Association of America (SAA), accepted the invitation by the Food and Drug Administration (FDA) to give input in the development of a guidance document for the performance of clinical trials in AS. A specific project group for this initiative was formed consisting of six working groups for the topics: scope of patients, definition of claims, signs and symptoms, function, structural damage, and methodological issues. These six groups reviewed the literature and prepared a proposal. During a two day public conference, all groups presented their proposals, which were open for discussion. Representatives from ASAS, SAA, FDA, pharmaceutical companies and other interested persons took part in the conference. After taking the various views into consideration, a final proposal for the guidance document was prepared and offered to the FDA. The resulting recommendations for conducting clinical trials in AS will be published in the near future.

Consensus statement for the use of anti-TNF agents

ASAS, with the majority of experts in the field of AS as members, also functions as a platform to discuss important matters in relation to other aspects of AS aimed at improving the outcome of the disease. A key breakthrough in the treatment of AS has been the availability of anti-TNF agents with major potential to alter the outcome for patients. In a specific workshop aimed at addressing the use of anti-TNF agents, various aspects related to initiation, monitoring, and stopping treatment were discussed. Preparation for the workshop involved a questionnaire, Delphi exercise, and discussions in small groups.4 This led to a consensus statement on the use of anti-TNF agents,5 which forms the basis for guidelines in various countries—for example, in relation to reimbursement policy.

Relationship between ASAS and OMERACT

ASAS also has close relations with OMERACT. By this collaboration, the work performed within ASAS is disseminated outside the group of experts in AS. The core sets defined and developed by ASAS have been formally endorsed by OMERACT and the International League of Associations for Rheumatology (ILAR).6 At the OMERACT conference in 2004, a full workshop was devoted to imaging in AS, organised by ASAS. Substantial work has been done with regard to validation of scoring methods for radiographs. During OMERACT 7 (Asilomar, 2004) a decision was taken with regard to the preferred scoring method. Magnetic resonance imaging, a new and promising tool in AS, is at a much earlier stage. Research on this topic was announced and discussed at the OMERACT 7 conference and will be boosted by new data evolving from ongoing trials.


There are still many areas of research in relation to outcome assessment, and the broader field of outcome of AS in general. Many projects are ongoing. Examples include: the evaluation of the use of the guidelines on anti-TNF treatment, development of criteria for an early diagnosis of AS, validation of spinal mobility measures, and assessment of quality of life, education, and physical therapy. The strength of ASAS is the enthusiasm of an international group of experts in the field, who are willing to devote time and effort to bring the ultimate goal, improvement of outcome of patients with AS, closer to reality.