Diagnosis of polymyalgia rheumatica (PMR) has started to move from the realm of clinical intuition toward a more objective approach, after the release of provisional classification criteria, published online March 2 and in the April issues of Arthritis & Rheumatism and the Annals of the Rheumatic Diseases. The criteria were developed as a collaborative project by the European League Against Rheumatism and the American College of Rheumatology.
In an accompanying editorial, Robert Spiera, MD, and Rene Westhovens, MD, PhD, emphasize that these are "provisional classification and not diagnostic criteria." As such, they need to be validated and are designed to facilitate research. Dr. Spiera is director of the Vasculitis and Scleroderma Program at the Hospital for Special Surgery in New York City, and Dr. Westhovens is professor and head of the Department of Rheumatology at Catholic University of Leuven in Belgium.
Dr. Spiera and Dr. Westhovens comment, "It seems clear that these criteria do not have adequate specificity or sensitivity to be applied to the approach of patients in the clinic, nor were they intended for such use. It is likely, however, that once published, such provisional criteria will be considered for use in practice by rheumatologists but even more so by primary care providers, who indeed are the ones more often diagnosing and even caring for patients with PMR." They suggest that the criteria might help clarify the diagnosis of PMR but, until validated, "cannot...supersede the importance of clinical sense."
A criteria working group convened in 2005 identified potential PMR criteria through systematic literature review, a consensus process, and wider survey. The proposed criteria were reviewed by both rheumatologists and nonrheumatologists. The working group then tested the criteria in a 6-month prospective cohort study of 125 patients with new-onset PMR and 169 patients without PMR who had conditions mimicking PMR, such as rheumatoid arthritis, connective tissue diseases, or shoulder conditions such as bilateral rotator cuff syndrome. Patients were recruited from 21 community-based and academic rheumatology clinics in 10 European countries and the United States.
The results of the prospective study suggest that the criteria will be useful for PMR classification. "Our classification algorithm had a C statistic of 81%, which exceeds the threshold of 80% that is conventionally considered to be useful in clinical decisionmaking. However, we suggest that the criteria are regarded as provisional at this point, awaiting validation in a separate cohort," the authors conclude.
The provisional criteria for PMR classification are:
* age ≥50 years,
* bilateral shoulder aching, and
* abnormal C-reactive protein and/or erythrocyte sedimentation rate,
* plus at least 4 points (without ultrasound, US) or 5 points (with US) from the following:
* morning stiffness that lasts longer than 45 minutes (2 points)
* hip pain or limited range of motion (1 point)
* the absence of rheumatoid factor or anticitrullinated protein antibody (1 point)
* absence of other joint involvement (1 point)
* if US is available, at least 1 shoulder with subdeltoid bursitis and/or biceps tenosynovitis and/or glenohumeral synovitis, and at least 1 hip with synovitis and/or trochanteric bursitis (1 point)
* if US is available, both shoulders with subdeltoid bursitis, biceps, tenosynovitis, or glenohumeral synovitis (1 point)
The authors emphasize that these criteria are provisional and require validation in a separate cohort.
Senior author Eric Matteson, MD, chair of rheumatology at the Mayo Clinic in Rochester, Minnesota, told Medscape Medical News, "This is mainly intended as a tool for classifying patients with this disease for purposes of being able to better study it. It does contain key features we associate with the disease diagnosis."
Response to Steroids Not Included in PMR Criteria
Dr. Matteson added, "One thing that is different from other 'diagnostic,' as well as classification, attempts for this disease is that these criteria do not use response to corticosteroids as a criterion. I see this as very important. Many inflammatory disease states (rheumatoid arthritis, for example) respond to corticosteroid trial. That response is very nonspecific. As well, if one is doing a clinical trial of new-onset PMR, it is very difficult to determine if the new drug does or does not work if the patient has already been treated with steroids."
The authors' list of unanswered questions for future research include whether PMR should be considered as a late-onset inflammatory arthritis, whether polymyalgic disease without peripheral synovitis can occur in RF-positive patients, whether PMR can be diagnosed in patients with normal acute-phase response, and the early use of disease-modifying antirheumatic drugs in PMR.
According to Dr. Matteson, an international validation study of the PMR criteria is in the planning stages, and clinical trials of early disease-modifying antirheumatic drug use in patients with PMR are also planned.
Supported by the American College of Rheumatology, the European League Against Rheumatism, and the Mayo Foundation. Additional support was provided by the Biobanque de Picardie, Amiens, France. Two coauthors' work was supported by the Ministerio de Ciencia y Tecnologia, Spain. Dr. Matteson, Dr. Spiera, and Dr. Westhovens have disclosed no relevant financial relationships. Complete conflict-of-interest information is available in the article.
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