What clinical and laboratory findings help predict whether a patient with early undifferentiated arthritis will develop Rheumatoid Arthritis?
Among patients with UA who do not meet the 1987 RA classification criteria, 33% will progress to RA (by 1987 criteria) over the following year, 33% will be diagnosed with another type of inflammatory arthritis, and 33% will undergo spontaneous remission. When using the newer 2010 RA classification criteria, 6% to 22% of patients with UA will progress to RA, 53% will have persistent UA, 3% will be diagnosed with another type of inflammatory arthritis, and 22% will undergo spontaneous remission. These differences likely reflect the improved sensitivity of the 2010 criteria (with a significant proportion of UA patients now classified as RA at the time of initial evaluation) as well as the mandate within the new classification criteria to rule out competing diagnoses as the cause of inflammatory arthritis before applying the criteria to a specific patient (improved specificity). Predictors of progression to RA by 2010 classification criteria include: 1) higher score on 2010 classification criteria at baseline (42% with a score of 5 will develop RA; therefore, number of involved joints, duration of symptoms, and presence of autoantibodies and elevated inflammatory markers are all important factors) and 2) grey scale synovitis on ultrasound.