Diagnosis

The diagnosis of rheumatoid arthritis can be very difficult, especially in the earlier stages when the symptoms are morning stiffness or achy joints. There is no one test that is used to diagnose RA, it is a combination of things. The diagnosis comes usually after a history and physical, in addition to some lab tests and studies. Following are the clinical features that are present for a RA diagnosis:

1. Inflammatory arthritis involving three or more joints
2. Positive rheumatoid factor and/or anti-citrullinated peptide/protein antibody
3. Elevated levels of C-reactive protein (CRP) or the erythrocyte sedimentation rate (ESR)
4. Diseases with similar clinical features have been excluded, particularly psoriatic arthritis, acute viral polyarthritis, polyarticular gout or calcium pyrophosphate deposition disease, and systemic lupus erythematous.
5. The duration of symptoms of more than six weeks

The classification of RA was updated in 2010, which includes scoring on multiple domains. You can see the full explanation at this link: http://www.rheumatology.org/practice/clinical/classification/ra/ra_2010.asp

The differential diagnosis includes a variety of diseases, including:

•    Viral polyarthritis
•      Systemic rheumatic disease such as lupus
•      Palindromic rheumatism
•      Hypermobility syndrome and fibromyalgia
•      Reactive arthritis and arthritis of IBD
•      Lyme arthritis
•      Psoriatic arthritis
•       Polymyalgia rheumatica
•      Osteoarthritis

The recommendation is to suspect in RA in an adult who presents with inflammatory polyarthritis, the evaluation should include a detailed history and physical, along with the labs that help confirm the diagnosis.

As you can see from the list of differential diagnoses above, it is difficult and certainly very hard to live with the possibility of any of these diseases. Receiving a diagnosis can be helpful to focus attention on treatment, but RA is not a disease that can be cured. It is a difficult chronic disease to have that will have many uncertainty and unknowns. Healthcare providers are available to help with any step of the process, but utilizing your support system during difficult times can be very important.

Resources: 

1. http://www.rheumatology.org/practice/clinical/classification/ra/ra_2010.asp

2. http://www-uptodate-com.offcampus.lib.washington.edu/contents/diagnosis-and-differential-diagnosis-of-rheumatoid-arthritis?source=search_result&search=rheumatoid+arthritis&selectedTitle=1~150