Standardizing the monitoring of outcome measures: imaging in psoriatic arthritis

The wide spectrum of manifestations of musculoskeletal inflammation in psoriatic arthritis makes standardized assessment of joint damage in psoriatic arthritis a challenge. Assessment of erosions and joint space narrowing on plain radiographs of the hands and feet has remained the benchmark for assessing damage in psoriatic arthritis. The methods used to assess damage have been mostly borrowed from those used in rheumatoid arthritis. Axial joint involvement has not been systematically addressed. Methods to assess spinal disease have been borrowed from those used in ankylosing spondylitis. Both ultrasound and MRI have demonstrated promise in the assessment of psoriatic arthritis. The Outcome Measures in Rheumatology Clinical Trials (OMERACT) group is involved in the development of valid, reliable and feasible methods for assessment of joint involvement in psoriatic arthritis.