Vasculitis: Diagnosing and Treating Polymyalgia Rheumatica (PMR)

Polymyalgia rheumatica (PMR) is an inflammatory disease affecting hundreds of thousands of adults over age 50 in the U.S. alone, mostly of northern European (Scandinavian) descent, with twice as many women as men afflicted. Despite some telltale symptoms, PMR has confounding mimics. Treatment with steroids is not only beneficial for PMR, but essential to avoid adverse events associated with its more serious first cousin, giant cell arteritis (GCA).

In this Q&A, Cleveland Clinic rheumatologist Mathilde H. Pioro, MD, MSc, FRCPC, discusses these conditions as part of a disease spectrum. As they can elude definitive diagnosis, Dr. Pioro offers insights for differential diagnoses, reviews medication alternatives and emphasizes critical timing parameters for treatment.

What might help clinicians in trying to pinpoint a diagnosis of PMR?

Dr. Pioro: PMR is recognized by its hallmark pain and stiffness in the shoulders and frequently the pelvic girdle. Patients often complain of pain when rolling over in bed from side to side. Many conditions can mimic PMR, including rotator cuff injuries, arthritis and other inflammatory conditions. While a physical exam, history and lab tests can be indicative, definitive diagnosis of PMR is not always clear cut.

While elevated ESR (erythrocyte sedimentation rate) and CRP (C-reactive protein) are characteristic with PMR, they are also present with infection, tissue ischemia, malignancy and other disease states. These other causes must be considered and excluded before diagnosing PMR. Negative results on both may be useful in ruling out PMR, since finding both normal ESR and CRP occur in less than 1 percent of PMR cases. Normal ESR is found in up to 22 percent of patients, however, so that finding alone does not exclude PMR. Diagnosis rests upon a classic history and physical exam, as well as exclusion of mimics.

After initiating treatment, how does a clinician know the diagnosis was correct?

Dr. Pioro: The response to steroids should be clear and strong, although it may take up to three weeks in approximately one-fourth of patients. The response is more dramatic with PMR than most of its mimics.

What is giant cell arteritis (GCA) and why do you discuss it alongside PMR?

Dr. Pioro: Giant cell arteritis is an inflammatory disease characterized by a rapid deterioration of blood vessels, often the temporal artery, the aorta and the orbital arterial supply. It is much rarer than PMR, but 10 to 20 percent of patients with PMR develop GCA, and almost half of patients with GCA have symptoms of PMR. It is important for clinicians to examine patients with symptoms of either disorder with the other in mind as well.

What are the most important things you want clinicians to know about GCA?

Dr. Pioro: Damage from GCA can occur swiftly and have permanent repercussions. If GCA is suspected, clinicians should begin high-dose steroids, even before confirmatory testing through temporary artery biopsy. With vision loss, it is particularly critical to do this as soon as possible to prevent permanence. Vision remains at risk for up to six days even after starting high-dose pulse steroids. It is essential to make an immediate referral to a rheumatologist and to have one-on-one communication with them.

Do we have solid guidelines for appropriate steroid administration for PMR and GCA treatment?

Dr. Pioro: There is no consensus on initial steroid dosing, maintenance therapy or a tapering schedule for either PMR or GCA, but in my experience, for patients with PMR, empirical use of oral methylprednisolone may sometimes be effective if prednisone fails to produce a dramatic improvement. Tapering at the end is a balancing act. I suggest that stepwise, alternative day decreases of 1 mg over two to four weeks might facilitate the taper when at very low doses.

Are there steroid-sparing medications that are effective for either or both conditions?

Dr. Pioro: Eighty-six percent of people develop steroid-related adverse effects after a 6.5-month regimen to reach 7.5 mg of prednisone daily, with side effects ranging from diabetes mellitus and hypertension to infection and cataracts. Clinicians understand the trade-offs involved and the desirability of alternatives.

Looking at the latest literature, methotrexate (MTX), while the drug of choice for rheumatoid arthritis, has a limited effect on PMR and only a modest impact on GCA. TNF inhibitors are ineffective. However, for GCA, we may have found a promising alternative to maintenance steroids in tocilizumab, an IL-6 inhibitor also used for treatment of rheumatoid arthritis. Tocilizumab has been found to successfully enable steroid tapering in GCA patients, while inducing and maintaining disease control.

Dr. Pioro recently wrote an article on PMR and GCA in Primary Care: Clinics in Office Practice (June 2018).