Clinical and laboratory assessments in rheumatoid arthritis and osteoarthritis.

Clinical and laboratory assessments in rheumatoid arthritis and osteoarthritis precede imaging methods in both defining diagnosis and determining response to therapy. Some assessments are similar in both diseases, e.g. measuring joint pain, the number of involved joints and functional impairment. There are also areas of difference; for example, rheumatoid arthritis is a systemic disease with immune disturbance and positive tests for rheumatoid factor and elevated acute phase markers while osteoarthritis is a more local disease with little systemic upset. In both diseases pain and progressive joint damage result in increasing disability. There is agreement on a core data set in rheumatoid arthritis which comprises: swollen joint counts, tender joint counts, pain assessment, patient's global assessment, an acute phase marker such as the ESR and a self-administered functional questionnaire. There is less agreement on the core data set in osteoarthritis, though pain and functional impairment are both important. Combined or overall indices have been used in both rheumatoid arthritis (e.g. the disease activity score) and in osteoarthritis (e.g. the Lequesne functional index), but there is no general agreement on their value. In both diseases plain radiology is useful to define diagnostic groups and follow progression in long-term studies. Mortality is increased in rheumatoid arthritis and is useful for defining the long term effects of the disease; little is known about mortality in osteoarthritis. Standardizing clinical methods is important and much work is needed in this area.