Tools Your Doctor Will Use to Diagnose RA
There are a number of tools a doctor uses to determine a diagnosis of rheumatoid arthritis (RA) as well as disease activity. This includes a thorough physical examination, taking a medical history, laboratory testing, and imaging (x-rays or MRIs). There are additional specialized tests that are used as well, such as joint aspiration, arthroscopy, and synovial fluid analysis.
When your doctor takes your medical history, he or she will ask you questions covering several key areas. These will include questions about your symptoms, family medical history, other medical problems you may have, and any medications you are taking.
During the medical history, your doctor will be interested in knowing about the type of pain you are experiencing, including:
- location and pattern of pain throughout the body
- how pain affects your mobility and lifestyle
- whether the pain is affecting your sleep or sleep quality
- whether the pain is causing fatigue.
Existing medical problems
Your doctor will also want to know about any other medical problems you have. There are some medical problems that tend to occur along with RA and may be suggestive of the disease. Additionally, it is important to give your doctor a complete list of any medications, vitamins, or supplements that you are currently taking.
Family medical history
In addition, your doctor will also ask about your family medical history. Since there is a hereditary component to RA, information about any close relative with RA (or any other autoimmune disease) may help your doctor get a complete picture of your risk.
A physical exam is another part of getting an RA diagnosis. Your healthcare provider will check your blood pressure, pulse rate, heart and lung function. In addition, your doctor will evaluate your joints, paying extra attention to function, swelling, and pain. If you have RA, the physical exam will also help your doctor determine the severity of your disease. Knowing the severity of your RA will be used to guide treatment decisions.
Laboratory testing helps form a complete picture to help determine your diagnosis. There are certain substances that tend to be present in the blood of patients with RA. High levels of common components of blood are suggestive of inflammatory disease. Most laboratory tests for RA look at:
- Rheumatoid factor (RF)
- Anti-citrullinated protein antibodies (ACPA) (including anti-cyclic citrullinated peptide [anti-CCP] and anti-mutated citrullinated vimentin [MCV] antibody tests)
- Erythrocyte sedimentation rate (ESR)
- C-reactive protein (CRP)
- Antinuclear antibody (ANA)
- Complete blood count (CBC)
Your doctor may have x-rays taken of symptomatic joints. X-rays can reveal signs of inflammation and damage (bone erosion) that are indicative of RA. Other imaging tests that may be useful in diagnosis of RA include magnetic resonance imaging (MRI) or an ultrasound.
Surveys to determine RA disease activity
There are several survey-type tools that have been developed to help doctors determine the extent of RA disease activity. These usually focus on joint activity, swelling, pain levels, and disability. These measures include, but are not limited to the following:1-3
- Health Assessment Questionnaire (HAQ): consists of the Physician Global Assessment (PGA), which is a binary yes/no clinical evaluation of presence of pain or swelling in any of 13 joints, bilaterally and the Patient Global Assessment (PtGA) asks patients to rate pain on a linear scale and to assess their ability to perform everyday tasks.
- Disease Activity Score for 28 joints (DAS 28): combines single measures into an overall continuous measure of RA disease activity. It includes a 28-swollen joint count (28SJC), 28-tender joint count (28TJC), erythrocyte sedimentation rate (ESR) and a PtGA or general health (GH) on a visual analog scale (VAS) for pain. It results in an overall disease activity score of high, low, or remission.
- American College of Rheumatology 20 (ACR 20): evaluates clinical improvement relative to an initial assessment and is commonly used as an efficacy endpoint for clinical trials in patients with RA. The ACR20 denotes at least 20 percent improvement in tender and swollen joint counts and in three of the following endpoints: global assessment by patients, global assessment by doctors, ESR or C reactive protein (CRP), patient's pain VAS, and Health Assessment Questionnaire Score
- Routine Assessment of Patient Index Data (RAPID3): includes a subset of core variables found in the Multi-dimensional HAQ (MD-HAQ), including an assessment of physical function, a PGA for pain, and a PGA for global health. RAPID3 scores are tallied by adding subsets of the MD-HAQ.
Your doctor may have used one or more of these tools for an initial diagnosis or to monitor treatment effectiveness over time. Unlike objective physical measurements like weight or height, these tools involve some level of subjectively based on perceptions of the patient, doctor, or both.
Other specialized tests
Other specialized tests that may be useful in assessing selected patients include analysis of synovial fluid, arthroscopy, and laboratory tests to detect possible infection.
Synovial fluid analysis
To do synovial fluid analysis, a needle is used to draw a sample of the fluid inside your joint cavity. Several tests are then performed on the synovial fluid, including a count of the cells present in the fluid, a search for uric acid crystals that may indicate gout, and a gram stain and culture to detect possible infection.
Arthroscopy involves inserting a fiberoptic camera through a tube (about the size of a straw) into the joint space to examine the inside of the joint. This procedure can be used to aid diagnosis. Sometimes a second incision is made and small surgical instruments are also inserted into the joint space through another tube for making repairs to damaged joint tissues or for removing bone or cartilage.