Outcome measures of disease activity in inflammatory arthritis

The most common types of chronic inflammatory arthritis are rheumatoid arthritis, psoriatic arthritis and ankylosing spondylitis. In order to assess the activity of these diseases and tailor therapy, several outcome measures have been developed. They include composite scores based on clinical findings, biochemical markers and patient questionnaires. This article discusses the most commonly used outcome measures and looks at their limitations in quantifying the complex clinical features of different types of inflammatory arthritis, focusing in particular on rheumatoid arthritis, psoriatic arthritis and ankylosing spondylitis.