Differentiating Polymyalgia Rheumatica (PMR) From Elderly-Onset Rheumatoid Arthritis (EORA)

Joint pain is a very common part of aging. You may feel sudden stiffness in your shoulders and hips after a night’s sleep or from sitting for a long period of time. This often points to a condition called polymyalgia rheumatica (PMR). But there is another condition that looks the same. It is called elderly-onset rheumatoid arthritis (EORA).¹

These 2 conditions can be hard to tell apart. But it is important to understand the difference between the conditions. The right diagnosis can help you get the best treatment plan.

Both conditions have similar symptoms

PMR and EORA often start with the same symptoms. Both cause joint pain and stiffness, often right after waking up or after a long period of rest. These joints include the shoulders and the pelvic girdle. This "shoulder-first" start can lead to a diagnostic "gray zone" for people over 50.¹

EORA frequently "masquerades" as PMR in its early stages. In younger people, rheumatoid arthritis (RA) usually starts in small joints like the fingers. But in older adults, EORA often starts in the shoulders or knees. The onset can be very sudden. Because both diseases cause similar shoulder pain, doctors must look for other clues.¹

Knowing your serological status

Blood tests are a key way to tell these diseases apart. Doctors look for markers called rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP). These are autoantibodies made by the immune system.¹

PMR is almost always "seronegative." This means the blood tests for RF and anti-CCP are negative. EORA can be different. Some people with EORA are "seropositive." This means they have these markers in their blood. If your test is positive for anti-CCP, you likely have EORA.¹

Knowing your serological status is important. Seropositive EORA is often more aggressive. It can cause more damage to your joints over time. Finding these clues helps your doctor choose the right medicine to help with your specific symptoms.¹

The role of musculoskeletal ultrasound

Imaging can help break the tie when blood tests are not clear. Musculoskeletal ultrasound is a great tool for this task. It allows doctors to see inside the joint without using radiation.²

In PMR, ultrasound often shows inflammation around the joint. A common finding is bilateral subdeltoid bursitis. This is inflammation of the fluid-filled sacs in the shoulders.²

In EORA, the findings are usually different. Ultrasound often reveals true joint erosions. It also shows synovial thickening. These signs mean the joint itself is under attack. Without the right care, these erosions can lead to permanent joint damage.²

Navigating the treatment overlap

The initial treatment for PMR and EORA can be similar. Both often respond well to steroids like prednisone. Some newer drugs called IL-6 inhibitors work for both conditions. These drugs block a protein that causes inflammation.¹

However, the "end game" for treatment is different. The goal for PMR is usually to find an "off-ramp." Most people with PMR can slowly stop taking their drug after 1 or 2 years.¹

The goal for EORA is different. It uses a "treat-to-target" approach. The target is total remission. This often requires lifelong treatment to keep the disease in check. Early and correct diagnosis ensures you stay on the right path for your long-term health.¹

Talk to your doctor

PMR and EORA share many characteristics. They both cause stiffness and inflammation in the joints. But their long-term paths are not the same. Doctors may use blood tests and an ultrasound to get a correct diagnosis.^1,2

Knowing your specific condition helps you and your healthcare team plan for the future. Talk to your doctor if you have new joint pain that does not go away.^1,2