The assessment of disease activity in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterised by progressive damage of diathrodial joints, with variable extra-articular manifestations. Joint damage begins early in the course of the disease as a consequence of the active inflammation, and can lead to progressive and irreversible disability. Successful treatment relies on patients attaining low disease activity or a state of remission, which have become achievable goals since the improved use of methotrexate (MTX) and the introduction of biological agents, such as tumour necrosis factor (TNF) inhibitors. To allow physicians to evaluate the indication and effect of particular therapies, accurate assessment of disease activity is necessary. Disease states in RA can be evaluated by a number of measures. These include signs and symptoms, such as counts of tender and swollen joints; laboratory measures like the acute phase response, which is a direct reflection of the underlying inflammatory activity; and patient-focused variables to measure pain and global assessment of disease activity. Some of these (and additional) measures are used in composite indices to assess disease activity or a disease activity state at any point in time and can inform the physician (and patient) about improvement (or deterioration) in disease activity from a particular level at baseline, to that seen at any specific time point. The accurate assessment of disease is, therefore, an important part of the care of patients with RA. However, it can be complex to perform in the clinical setting, so new and simplified measures have evolved. Next to disease activity, the disease outcome is of utmost importance, in particular disability and quality of life, which are assessed using patient reported questionnaires. Radiographic assessment of structural changes is also an important outcome of RA and mirrors joint damage. The latest developments in the field are discussed and will help to identify patients who can benefit most from today's opportunities of pharmacotherapy, allowing optimisation of patient care.