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PMR Guidelines Spell Out Ultrasound's Role

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New Classification Criteria Shouldn't Replace Clinical Intuition in Practice

While the newly proposed polymyalgia rheumatica classification criteria will likely facilitate future research, it is important to emphasize that they are provisional and not diagnostic, Dr. Robert F. Spiera and Dr. Rene Westhovens said in an accompanying editorial.

The point that classification criteria are useful for defining patient groups for studies but are not intended to define diagnoses in clinical practice is particularly relevant in PMR, a syndrome that is "common, eminently treatable, and most often initially encountered by and treated by primary care providers rather than rheumatologists," they wrote (Arthritis Rheum. 2012;64:955-7).

As such, the criteria will undoubtedly be looked at by clinicians in practice, therefore, their performance in terms of sensitivity and specificity must be well understood and considered, they said.

The sensitivity of the scoring algorithm developed for classifying patients as having PMR in this study was 68%. Since PMR can be a very vague syndrome, and since corticosteroid treatment is generally very beneficial in patients with PMR, relying on these provisional classification criteria to determine which patients should receive treatment would could leave about a third of patients untreated and left with unnecessary suffering, Dr. Spiera explained in an interview.

He likened the diagnosis of PMR – a "difficult to define syndrome of inflammatory pain and stiffness in older people" – with U.S. Supreme Court Justice Potter Stewart’s 1964 attempt to define pornography: "... I could never succeed in intelligibly doing so, but I know it when I see it," Justice Stewart said.

Similarly, with PMR, most clinicians know it when they see it.

"Although the authors indicate the dangers of overdiagnosis of this condition because of the potential of overusing corticosteroids, when used judiciously in relatively low doses with appropriate attention to the management of comorbidities, this therapy can have very favorable risk-benefit profile," he and Dr. Westhovens wrote.

They noted that another factor limiting the generalizability of the criteria is the inclusion of elevated sedimentation rate and/or CRP; in practice, as many as 20% of patients with "fairly classic" PMR have no such elevations.

The criteria would appropriately exclude a patient without an elevated sedimentation rate and/or CRP from inclusion in a clinical trial, but in practice this shouldn’t preclude the use of corticosteroids, Dr. Spiera said.

"Although these criteria afford clinicians a basis for more objectively examining their diagnosis, and while allowing for a greater precision than Justice Stewart’s definition of pornography, they cannot yet be assured to supersede the importance of clinical sense to which that rather vague definition speaks," he and Dr. Westhovens concluded.

Dr. Spiera is director of the vasculitis and scleroderma program at the Hospital for Special Surgery, N.Y. He disclosed that he is conducting an investigator-initiated PMR drug trial supported by Roche/Genentech. Dr. Westhovens is with University Hospital Katholieke Universiteit Leuven, Belgium.


 

FROM ARTHRITIS & RHEUMATISM

Unexplained shoulder pain and abnormal ultrasound findings of those large joints are part of provisional criteria published on polymyalgia rheumatica.

To be diagnosed with polymyalgia rheumatica (PMR) under the criteria proposed jointly by the American College of Rheumatology and the European League Against Rheumatism, patients should be at least 50 years old, have morning stiffness lasting at least 45 minutes, new hip pain, and elevated C-reactive protein and/or erythrocyte sedimentation rate.

ACR and EULAR based their criteria on findings from a prospective, international, multicenter cohort study, are published in the April issue of Arthritis & Rheumatism.

Additional validation in an external data set is required, and the criteria should not be used for diagnostic purposes, but they do have value for identifying the most appropriate patients for enrollment in clinical trials, and thus could pave the way for new therapeutic approaches and novel treatments for the inflammatory disease, Dr. Bhaskar Dasgupta of Southend University Hospital, Westcliff-on-Sea, U.K. and his colleagues reported (Arthritis Rheum. 2012 April;64:943-54).

PMR is a common condition, but its clinical management varies widely, due largely to considerable uncertainty with respect to diagnosis, disease course, and management, according to Dr. Eric L. Matteson, the study’s senior author, who noted in an interview that a lack of classification criteria has hampered development of rational therapeutic approaches because of difficulties in grouping together appropriate patients for enrollment in clinical studies.

"We have no good, established, and in any way validated criteria for classifying patients with having PMR. All previous criteria were based mainly on expert opinion, so what we did here was look at expert opinion about components of the disease that would help us classify a patient as having PMR, then tested to see which of the features in patients who appear to have PMR by expert diagnosis at the outset were most effective in identifying, for classification purposes, patients as having PMR after they were followed for 6 months," said Dr. Matteson, chair of rheumatology at the Mayo Clinic in Rochester, Minn.

The criteria were based on the findings of a criteria development work group convened in 2005 in response to an ACR/EULAR initiative. The group performed a systematic literature review, and through a multiphase process, identified candidate classification criteria, which were ultimately investigated in the 6-month prospective cohort study of 125 patients with new-onset PMR and 169 comparison patients with conditions mimicking PMR.

A scoring algorithm was developed based on four criteria: morning stiffness for greater than 45 minutes (2 points); hip pain/limited range of motion (1 point), absence of rheumatoid factor (RF) and/or anticitrullinated protein antibody (2 points), and absence of peripheral joint pain (1 point).

"A score of 4 or higher had 68% sensitivity and 78% specificity for discriminating all comparison subjects from PMR. The specificity was higher (88%) for discriminating shoulder conditions from PMR and lower (65%) for discriminating RA from PMR. The C statistic for the scoring algorithm was 81%," the investigators said.

The absence of peripheral synovitis or positive RF serology increased the likelihood of PMR.

Additionally, ultrasound was found to significantly improve the specificity of the clinical criteria, improving the C statistic to 82% when added to the scoring algorithm.

"Patients with PMR were more likely to have abnormal ultrasound findings in the shoulder (particularly subdeltoid bursitis and biceps tenosynovitis), and somewhat more likely to have abnormal findings in the hips than [do] comparison subjects as a group," the investigators said, adding that PMR could not be distinguished from RA on the basis of ultrasound, but could be distinguished from non-RA shoulder conditions and subjects without shoulder conditions.

Adding ultrasound to the scoring algorithm improved the C statistic of 82%.

The ultrasound finding mark the first time this technology has been systematically utilized in a longitudinal study for this purpose, Dr. Matteson said, adding that there are, indeed, typical findings on ultrasound in PMR, and although ultrasound alone can’t be used to identify PMR as opposed to RA, the findings can be helpful for classification of patients with PMR.

He also noted that the ultrasound features seen in PMR at the outset improved with treatment.

Patients and controls in the study were recruited from 21 community-based and academic rheumatology clinics in 10 European countries and the United States. All were aged 50 years or older, had new-onset bilateral shoulder pain, and no corticosteroid treatment within 12 weeks before the study. Patients had received a diagnosis of PMR, and corticosteroid treatment was initiated after enrollment.

The non-PMR comparison cohort included subjects with a variety of conditions that need to be distinguished from PMR, in both primary and secondary care, the investigators said.

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