Rheumatoid arthritis: Clinical sciences

Rheumatoid arthritis is a chronic, autoimmune disorder that involves symmetric inflammation of the synovial joints, leading to joint effusion with eventual destruction of cartilage and bones. This results in joint pain and severe functional impairment of the affected joints. Since there are no pathognomonic laboratory or imaging findings associated with rheumatoid arthritis, the diagnosis is clinical, meaning it is based on historical and physical exam findings.

Now, if your patient presents with signs and symptoms suggestive of rheumatoid arthritis, first you should obtain a focused history and physical exam. Your patient may report joint stiffness in the morning, or with prolonged inactivity, that lasts 30 minutes or longer, as well as joint swelling. Additionally, there might be nonspecific systemic symptoms such as fatigue, malaise, and depressed mood, as well as poor appetite. Patients usually report that these symptoms have been ongoing for more than 6 weeks.

Physical exam findings typically include symmetrical swelling and joint tenderness to palpation of the smaller joints. The most commonly affected joints are the proximal interphalangeal or PIP joints, and metacarpophalangeal or MCP joints. Typically, if one hand is involved, it is likely the other hand is also involved. You may also find swelling and tenderness of the wrists and metatarsophalangeal, or MTP, joints. Keep in mind that sometimes larger joints can also be involved. When a larger joint is affected, you might also notice a joint effusion.

Now, here’s a clinical pearl to keep in mind! If your patient has less than 30 minutes of morning stiffness, then consider mechanical wear and tear, like osteoarthritis instead of rheumatoid arthritis, where the stiffness can last more than 30 minutes. Another way to distinguish between the two is by the pattern of affected joints. Rheumatoid arthritis tends to be symmetric, meaning that joints on both sides of the body are equally affected, whereas patients with osteoarthritis are more likely to have asymmetric joint involvement.

Now, if the disease has been present for some time, the underlying joint inflammation can cause the surrounding structures to shorten, stiffen, and become constricted, which eventually results in contractures. Some important contractures to keep in mind when approaching a patient with rheumatoid arthritis include ulnar deviation of the MCP joints; Boutonniere deformities, where there is persistent flexion of the PIP joints and hyperextension of the DIP joints; and Swan-neck deformities, where there is persistent hyperextension of the PIP joints and flexion of the DIP joints. All of these findings are highly suggestive of rheumatoid arthritis, so at this point, you can make the diagnosis.

Now, here’s another clinical pearl to keep in mind! Rheumatoid arthritis is characterized by polyarthritis, or having multiple joint involvement. If you only find one joint with arthritis, or monoarticular arthritis, you should consider another diagnosis, such as septic arthritis or gout.

Alright, once you’ve diagnosed rheumatoid arthritis, your next step should be to determine the disease prognosis and severity. To do so, you have to order labs, including CBC, antinuclear antibody, or ANA; anti-cyclic citrullinated peptide, or anti-CCP antibody; rheumatoid factor, or RF; ESR; and CRP. Next, order imaging, including an X-ray of the affected joints.

Depending on your concern for other conditions, you can also order an ultrasound of the affected joints to evaluate for evidence supporting another diagnosis. For example, abscess formation indicates septic arthritis. If a large joint is involved, you might also need to perform an arthrocentesis with cell count, gram stain, cultures, and crystal analysis. Remember, this lab and imaging workup is not diagnostic, but prognostic, and results will help you determine disease severity and risk.

Alright, now moving on to the lab findings, which may reveal anemia of chronic disease and thrombocytosis on CBC. You may also find a positive ANA, anti-CCP, or RF, but negative values do not rule out rheumatoid arthritis. A negative ANA does rule out systemic lupus erythematosus, also called SLE, however. Finally, ESR and CRP could be normal or elevated!

Now, here’s a clinical pearl to keep in mind! Anti-CCP and RF are antibodies that define a patient with rheumatoid arthritis as “seropositive”. Seropositive individuals are at higher risk for disease complications, like bony erosions. Though they are part of the classification criteria, they are not required to make the diagnosis of rheumatoid arthritis, as some patients are “seronegative”. For example, RF is also seen in conditions like infections, malignancies, and even healthy individuals without organic disease.