Rheumatoid arthritis (RA) is a condition that causes symmetrical inflammation of the joints, which affects up to 1% of our population. It is thought to arise through both genetic and environmental factors. Important environmental factors are thought to include cigarette smoking and dental disease.
The early diagnosis of RA is important as it is now understood that there is a twelve-week ‘window of opportunity’. If therapy is started during this time, patients are more likely to achieve a low disease activity and show less progression on x-rays and scans of the joints. In addition if a patient sees a specialist within this period there is a higher chance of the patient not requiring medication for the RA in the long-term.
The 2009 National Audit Office reported that there was an average of a nine-month interval between the onset of the symptoms and when the diagnosis of RA was made. This is in part due to a delay in the patient seeing a specialist. However, half of all patients who go on to be diagnosed with RA are seen four times by their GP before they see a specialist, and nearly one in five patients are seen on eight occasions before a referral is made to a specialist.
When evaluating a patient with suspected RA a careful history and examination is required. Features that are suggestive of a diagnosis of RA include:
- Early morning stiffness of more than 30 minutes duration
- Swelling at three or more joints
- Involvement of the wrists, small joints of hands and feet
- Duration of symptoms greater than six weeks
Blood tests known as inflammatory markers are often elevated, however they may be normal in a minority of patients. Other useful blood tests include Rheumatoid Factor (RF) and antibodies to Cyclic Citrullinated Peptide (CCP). Again, these may be normal in patients (in which the RA is then termed ‘sero-negative disease’). RF is positive in between 5-10 % of people who do not have RA. In early RA, RF is positive in 50% of patients, and this increases to 80% in late disease, it is also found in up to 20-30% of patients with a disease called Systemic Lupus Erythematosus (SLE) and is strongly associated with cryoglobulinemia. RF is therefore said to have poor ‘specificity’ in RA (meaning a positive result is not specific to a diagnosis of RA) but if it is present in high levels (greater than three times the upper limit of normal) then the result is usually significant. CCP antibodies are a much better test for RA because they have a specificity of 95-98%, although the sensitivity is similar to that of Rheumatoid Factor. This means that if a patient is CCP positive it is very likely that they have rheumatoid arthritis or will go on to develop the disease.
X-ray films in early RA are often normal, although they may show soft tissue swelling or thinning of the bones around the joint (periarticular osteopenia) (Figure 1). A far more sensitive test for RA is the use of Power Doppler Ultrasound. Power Doppler ultrasound is able to detect slow blood flow in the small blood vessels around the joint and thus identifies areas of new blood vessel formation (neovascularization) that is seen when a joint is inflamed (Figure 2).
Once a diagnosis of RA has been made, patients are started on Disease Modifying Therapy ideally within the twelve-week window of opportunity. Methotrexate is one of the most effective treatments in the management of RA and remains the ‘anchor drug’ in the treatment of this disease. Corticosteroids are used to achieve rapid disease control. Often injections into the muscle or joint are chosen to reduce the effects of long-term steroid use. In early disease patients require regular review by their specialist to allow their treatment to be adjusted and achieve tight disease control. If the disease remains active despite the use of two disease-modifying drugs, the patient may be suitable for what is known as a ‘biologic therapy’. Biologic therapies are novel antibodies that reduce the activity of the messaging proteins that play the key role in inflammation, known as cytokines (for example tumour necrosis factor, TNF).
Today we do have very effective treatments for Rheumatoid Arthritis. We need to optimize the management of these patients by starting treatment early, which ultimately relies on early recognition of symptoms followed by early referral to specialist care.
Figure 1: Plain xray radiograph in Early Inflammatory Arthritis showing periarticular osteopenia and soft tissue swelling of left fourth proximal inter-phalangeal joint.
Figure 2: Power Doppler ultrasound image of metacarpophalangeal joint. Synovial thickening and active power doppler signal indicate synovitis.