Preventing the Progression From Undifferentiated Arthritis to Rheumatoid Arthritis: The Clinical and Economic Implications
Published Online: November 19, 2010
Michael H. Schiff, MD
Over the past few years, the management of rheumatoid arthritis (RA) has emphasized early, aggressive therapy with traditional diseasemodifying antirheumatic drugs (DMARDs) and/or antirheumatic biologic agents. This has been the result of a greater understanding of the pathophysiology of undifferentiated arthritis (UA) and RA, along with the availability of several biologic agents that down-regulate aspects of the autoimmune response that contribute to RA.
Approximately 40% to 50% of patients with UA experience spontaneous remission while roughly 30% progress to RA, and the remainder develop other conditions.1,2 Researchers have investigated criteria that can help identify those patients with UA who have a high probability of progressing to persistent and/or erosive RA. Once reliable criteria have been defined, the next question is whether active therapy, with either traditional DMARDs or antirheumatic biologic agents, can be effective in slowing or preventing disease progression. Clinical trials demonstrate that early treatment can delay or stop disease progression.3-6 From a managed care perspective, limiting treatment to only those patients with UA who would most benefit from active intervention has significant implications.
This article reviews the latest research supporting efforts to identify patients with UA who are at high risk of progressing to persistent and/or erosive RA, and offers insights on therapeutic approaches for these patients.
Defining Undifferentiated Arthritis
The term "undifferentiated arthritis" was incorporated into studies performed by the Leiden Early Arthritis Clinic in the Netherlands to describe cases of inflammatory arthritis where a specific diagnosis could not be made (Table 1).1,7,8 The question that follows is, why is UA important?
UA to RA Progression
Disease progression in patients who initially present with UA is comparable to that in patients who are initially diagnosed with RA. A study by van Aken and colleagues compared disease progression in patients who initially presented with UA and progressed to RA within 1 year (UA-RA group; n = 92) with disease progression in those who initially presented with RA (RA-RA group; n = 62) based on the 1987 American College of Rheumatology (ACR) criteria.1 Outcome measures were followed for 4 years following initial presentation.
No significant differences between the 2 groups were observed during any follow-up period (years 1, 2, 3, and 4) for radiographic progression of joint damage (as measured by Sharp/van der Heijde score) or disease activity and functional capacity (as measured by Health Assessment Questionnaire [HAQ] or Disease Activity Score [DAS]). Similar disease progression was observed in both groups despite more patients in the RA-RA group initiated on a DMARD by 3 months after presentation (100% vs 46%). This study suggests that patients with UA who eventually progress to RA have the same outcomes as those initially diagnosed with RA.
Predicting UA to RA Progression
Prediction rules are important tools in determining which patients with UA will progress to RA. The first validated prediction rule was developed in Europe and published in 2008. It used patient information that is regularly gathered during the initial office visit9,10-age, gender, number and types of joints involved, duration of morning stiffness, C-reactive protein level, and serologic assay results (presence of rheumatoid factor [RF] and anti-citrullinated protein antibody [ACPA]). When applied to 3 independent cohorts of patients with early-onset UA, this prediction rule accurately estimated the risk of developing RA in more than 75% of the patients with UA.10
ACR/EULAR RA Classification Criteria, 2010
In September 2010, the ACR, in collaboration with the European League Against Rheumatism (EULAR), released the updated RA classification criteria with the goal of distinguishing newly presenting patients with undifferentiated inflammatory arthritis who had a high probability of developing persistent or erosive RA (Table 2).11 These represent a significant change from the 1987 ACR criteria, which were not designed to identify patients with early RA or those at high risk of progressing to RA.7,12 The authors emphasize that the 2010 scoring system requires testing in various patient cohorts to demonstrate its validity. It will be important to determine if these criteria perform better for some patient cohorts than others and allow accurate individualization of treatment decision-making.
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