Inflammatory lookalikes: polymyalgia rheumatica, giant cell arteritis
Inflammatory disorders such as polymyalgia rheumatica and giant cell arteritis present similar symptoms, but require individualized diagnoses and understanding for effective treatment.
Marcia Friedman, MD, assistant professor of arthritis and rheumatic diseases and the director of the Oregon Health & Science University’s Vasculitis Center, spoke with Healio about symptoms, diagnoses, treatment and increased risks associated with these conditions.
Healio: What are indicators of Polymyalgia Rheumatica vs. Giant Cell Arteritis?
Friedman: Polymyalgia rheumatica (PMR) and giant cell arteritis (GCA) are inflammatory disorders that occur exclusively in adults over age 50, with a peak in the 70s and 80s. PMR causes pain and stiffness in the hips and shoulders. GCA is a vasculitis causing inflammation of medium to large sized blood vessels in the head and neck. Patients who have GCA experience headaches, jaw fatigue and/or vision changes. Untreated, GCA can lead to vision loss and strokes. PMR and GCA are strongly related conditions. About 20% of people with PMR develop GCA, and 50% of people with GCA also have PMR. Both conditions are highly inflammatory leading to fatigue, weight loss, low grade fevers and night sweats.
Healio: What presenting symptoms prevent an accurate diagnosis?
Friedman: The biggest challenge with diagnosing PMR and GCA is that both present with vague symptoms.
PMR presents with pain and stiffness in the hips and shoulders, but of course common problems like arthritis, tendonitis or bursitis can cause similar symptoms.
GCA is even more difficult, and the stakes are higher. The most common symptom of GCA is a headache (usually over the temples). However, of course most headaches are not caused by GCA. This makes the diagnosis notoriously challenging. Other symptoms of GCA include jaw fatigue (because the jaw muscle is not getting enough blood supply), and vision changes (loss of vision or double vision).
Healio: What are differences in imaging or biomarkers when making a diagnosis?
Friedman: Both PMR and GCA typically cause very high blood inflammatory markers. However, inflammatory markers can be elevated for many reasons, and there is currently no blood biomarker that can diagnose or distinguish these conditions.
Imaging does not play a major role in PMR. Imaging is being intensively studied for the diagnosis of GCA, however at this time imaging reliability is very operator and site dependent.
Healio: Is an erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) test more accurate in making a diagnosis, or is obtaining a biopsy still the best method?
Friedman: The best test for GCA is a biopsy of the temporal artery, which is minimally invasive and catches up to 90% of cases. The temporal artery biopsy should ideally be done within 2 weeks of starting steroids.
ESR and CRP are almost always elevated in GCA, however ESR and CRP can be elevated for many different reasons including infections, trauma, cancer, chronic inflammatory conditions, autoimmune diseases, kidney disease and many other causes. For this reason, and ESR or CRP elevation alone is not usually enough to diagnose this GCA.
Healio: How may a rheumatologist diagnose and treat PMR or GCA vs. an ophthalmologist?
Friedman: Rheumatologists and ophthalmologists treat GCA in essentially the same way.
However, primary care doctors are often the first providers to see a patient with PMR or GCA. In rare cases, the first presenting symptom of GCA is vision loss; in these cases, the patient is often first seen/diagnosed/treated by an ophthalmologist. Patients who are suspected to have PMR/GCA are often referred to rheumatologists to confirm the diagnosis and manage the treatment.
PMR is typically treated with prednisone at doses of 15 to 30 mg/day with a slow taper over 1 to 2 years. GCA, on the other hand, requires much higher initial steroid doses (60-80 mg/day) and again a slow taper over at least 1 to 2 years.
Unfortunately, it is very common for patients with PMR or GCA to suffer flares of their disease while tapering; when this happens, we briefly increase steroids and then continue to taper. For this reason, it can take a long time to treat GCA/PMR. There are also several other medications available to treat GCA, including tocilizumab and methotrexate, which may help taper steroids faster. Tocilizumab is an FDA-approved medication for the treatment of GCA. It is an immune-suppressing medication and carries several risks. Patients taking tocilizumab often have normal inflammatory markers, making this biomarker unreliable to assess disease activity.
Healio: Do PMR and GCA carry the same risk for cardiovascular disease?
Friedman: Inflammation is known to increase the risk for cardiovascular disease. Many, if not most, inflammatory diseases are associated with an increased risk for cardiovascular disease — PMR and GCA are likely no exception.
However, the other issue to consider is that prolonged corticosteroid treatment is itself associated with increased cardiovascular risk. Corticosteroids may increase blood pressure, lead to weight gain and cause or worsen diabetes. So, we have to strike a balance between calming down the excessive inflammation and using as little corticosteroid as possible to do so. It is also important that patients who are taking corticosteroids for PMR or GCA are working closely with their primary care doctors to make sure they control their blood pressure, diabetes and other risk factors of cardiovascular disease.
Healio: How do diet and exercise play into treating GCA and PMR?
Friedman: We do not know of any dietary or exercise programs that treat PMR or GCA itself. In fact, when someone has active PMR inflammation, exercise or physical therapy would be extremely difficult due to intense pain and stiffness.
However, once starting a treatment plan, diet and exercise are extremely important to keep patients healthy while undergoing treatment for PMR and/or GCA. Corticosteroids, which are necessary to treat these conditions, have many side effects including diabetes, high blood pressure and weight gain. Eating healthy and exercising are the best things pateints can do to keep themselves healthy while being treated for PMR or GCA.
Healio: What supplements or alternative therapies may benefit a patient with GCA or PMR?
Friedman: We do not know of any supplements or alternative therapies that may benefit either PMR or GCA.
However, when patients are taking corticosteroids, vitamin D and calcium are very important to help prevent bone loss caused by prednisone.
Healio: What are unmet needs in this demographic?
Friedman: We have so many unmet needs in GCA! Treatment is one unmet need. We always say that the only person who hates steroids more than a rheumatologist is a patient. We have made progress in finding treatments that reduce the need for steroids, but we still need long-term safer and more effective medications.
The most pressing unmet need in GCA is a biomarker. Despite being a relatively common form of vasculitis, we do not have a blood biomarker to reliably diagnose or rule out this disease. This leads to both overtreatment, and missed diagnoses. My research focuses on developing novel blood and tissue biomarkers, which can diagnose GCA, distinguish PMR from GCA and predict flares of disease.