Diagnosing rheumatoid arthritis (RA) in the early stages can be difficult. There is no single test that can clearly identify rheumatoid arthritis. Instead, doctors diagnose rheumatoid arthritis based on factors that are strongly associated with the disease. The American College of Rheumatology uses this list of criteria:
Morning stiffness in and around the joints for at least one hour.
Swelling or fluid around three or more joints simultaneously.
At least one swollen area in the wrist, hand, or finger joints.
Arthritis involving the same joint on both sides of the body (symmetric arthritis).
Rheumatoid nodules, which are firm lumps in the skin of people with rheumatoid arthritis. These nodules are usually in pressure points of the body, most commonly the elbows.
X-ray changes in the hands and wrists typical of rheumatoid arthritis, with destruction of bone around the involved joints. However, these changes are typical of later-stage disease.
Rheumatoid arthritis is officially diagnosed if four or more of these seven factors are present. The first four factors must have been present for at least six weeks. More recently, guidelines have changed somewhat in an attempt to diagnose RA in its earlier stages.
Because of these difficulties, a proper diagnosis is often missed early on. In fact, the average time between the onset of symptoms and the official diagnosis of rheumatoid arthritis is almost nine months.