Abstract

Abstract Objective To determine whether patients with undifferentiated arthritis (UA; inflammatory, nontraumatic arthritis that cannot be diagnosed using current classification criteria) benefit from treatment with methotrexate (MTX). Methods The PRObable rheumatoid arthritis: Methotrexate versus Placebo Treatment (PROMPT) study was a double‐blind, placebo‐controlled, randomized, multicenter trial involving 110 patients with UA who fulfilled the American College of Rheumatology (ACR) 1958 criteria for probable RA. Treatment started with MTX (15 mg/week) or placebo tablets, and every 3 months the dosage was increased if the Disease Activity Score was >2.4. After 12 months, the study medication was tapered and discontinued. Patients were followed up for 30 months. When a patient fulfilled the ACR criteria for RA (primary end point), the study medication was changed to MTX. Joint damage was scored on radiographs of the hands and feet. Results In 22 of the 55 patients (40%) in the MTX group, UA progressed to RA compared with 29 of 55 patients (53%) in the placebo group. However, in the MTX group, patients fulfilled the ACR criteria for RA at a later time point than in the placebo group ( P = 0.04), and fewer patients showed radiographic progression over 18 months ( P = 0.046). Conclusion This study provides evidence for the efficacy of MTX treatment in postponing the diagnosis of RA, as defined by the ACR 1987 criteria, and retarding radiographic joint damage in UA patients.