Abstract

Undifferentiated arthritis (UA) is defined as an inflammatory oligoarthritis or polyarthritis in which no definitive diagnosis can be made. We performed a literature review to assess the efficacy of various drug therapies in patients with UA. The literature search was conducted using electronic databases Pubmed, EMBASE and MEDLINE in adults with UA or early arthritis (not fulfilling the American College of Rheumatology (ACR) 1987 or ACR/European League Against Rheumatism (EULAR) 2010 criteria for rheumatoid arthritis). Drug therapy consisted of disease modifying antirheumatic drugs (DMARDs), biological agents and oral, intramuscular or intra-articular corticosteroids. Nine publications on eight randomised controlled trials (RCTs), two publications on two uncontrolled open-label trials and seven publications on three cohort studies were included. Temporary treatment with methotrexate (MTX), abatacept and intramuscular corticosteroids were demonstrated in RCTs with 12 months to 5 years follow-up to be more effective than placebo in suppressing disease activity or radiological progression. One study suggests that DMARD combination therapy is, at least after 4 months, superior to MTX monotherapy in patients with UA at high risk of developing persistent arthritis. The open-label uncontrolled trials and cohort studies also suggested that early treatment may provide immediate suppression of inflammation. The long-term benefit of early treatment in UA remains unclear. In conclusion, patients with UA benefit from early treatment with MTX. Combining multiple DMARDs or DMARDs with corticosteroids and biological agents may be even more beneficial. However, which treatment may provide the best results or may alter the disease course has still to be determined. More RCTs with longer follow-up time are needed.