Diseases Easily Confused with RA

Making a diagnosis of rheumatoid arthritis is often tricky. With no single test that confirms or eliminates the disease, the diagnosis of RA is based on a physical exam, patient history, laboratory tests and often imaging. However, symptoms of RA, such as pain, swelling and fatigue, are not exclusive to the disease. And correct diagnosis is important in choosing an appropriate treatment plan.

A number of diseases, such as lupus, fibromyalgia or Sjögren’s syndrome, may easily be confused with RA, or coexist in a patient. Arthritis symptoms might develop following certain infections, such as Lyme disease, tuberculosis, gastrointestinal infection or sexually-transmitted diseases. Patients with certain cancers, such as large granular lymphocyte (LGL) leukemia, have an increased incidence of RA, and acute leukemia in children may even be misdiagnosed as idiopathic juvenile arthritis.

In addition to the conditions mentioned above, here are seven diseases that could be misdiagnosed as rheumatoid arthritis:

Osteoarthritis (OA)

Osteoarthritis is the most common condition misdiagnosed as rheumatoid arthritis, according to a recent Colombian study. Of 2,478 patients referred by general practitioners to a specialized center with a presumed diagnosis of RA, it was found that 993 patients (40.1%) had been misdiagnosed. The correct diagnosis in 65 percent of the misdiagnosed patients was osteoarthritis (12).

Potentially confused with seronegative RA, inflammatory osteoarthritis is an aggressive, erosive subtype of primary osteoarthritis that affects 5 to 10 percent of those with OA. The periodic inflammation results in knobby, painful, inflamed knuckles and fingers, while the wrists and metacarpophalangeal joints are not involved. As a form of OA, blood tests show no increases in erythrocyte sedimentation rate (ESR) or C-reactive protein, and antinuclear antibody and rheumatoid factor testing will be negative (7).

Reactive arthritis (ReA)

Reactive arthritis (ReA), formerly called Reiter’s syndrome, is an autoimmune condition that develops in response to an infection. It has been associated with gastrointestinal (GI) infections with Shigella, Salmonella, Campylobacter and other organisms, as well as with genitourinary (GU) infections (especially with chlamydia trachomatis) spread through sexual contact. Symptoms, which may include arthritis, conjunctivitis, or urethritis, usually occur about one month following infection. ReA affects more men than women.

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Conditions that Resemble Rheumatoid Arthritis