Swelling of the MCP and PIP joints at inclusion and follow-up. Joint swelling (mean and 95% confidence interval [CI]) of the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints of the hands at inclusion and at 2 and 4 years follow-up in rheumatoid arthritis patients with (CCP+) and without (CCP-) anti-cyclic-citrullinated peptide antibodies. L, left; R, right.
van der Helm-van Mil et al. Arthritis Research & Therapy 2005 7:R949-R958 doi:10.1186/ar1767