Background In 2010 the new ACR/EULAR classification criteria for rheumatoid arthritis (RA criteria) were published. The prospects for early diagnosis and treatment have increased over the past decades, partly driven by the theory of a window of opportunity. This theory even implies the possibility of preventing development of RA if aggressive treatment is started early.
Objectives We wanted to study the 2-year outcome of patients with arthritis of less than 16 weeks duration, who fulfilled the RA criteria at baseline with a special focus on the impact of duration of joint swelling at baseline.
Methods 1084 patients (age 18-75 years) were included in the NOR-VEAC (Norwegian Very Early Arthritis Clinic) study from 2004 to 2010, i.e. before the RA criteria were implemented. Patients with crystal arthritis, septic arthritis, osteoarthritis and arthritis due to trauma were excluded. 234 patients (21.6%) fulfilled the RA criteria at baseline. 202 of these had information about DMARD use and were included in the current study.
The relationship between resolved arthritis (defined as no swollen joints at last visit and never used DMARDs) and duration of joint swelling, as well as other factors, was examined. Duration was treated as a non-linear continuous variable as well as divided into categories. Mann-Whitney U, Fisher's exact and Chi-Square tests were used for the statistical analyses.
Results Duration of joint swelling [median (25-75 percentile)] was 64 (38-83) days, mean (SD) age 52 (14) years, 62% were females, 60% anti-CCP positive, and 69% anti-CCP and/or RF positive. Tventy-three out of 202 (11.4%) patients had resolved arthritis. A statistically significant relationship was found between duration of arthritis at baseline and resolution of arthritis without exposure to DMARDs (Mann-Whitney U p=0.01). In cases with very short (0-2 weeks) duration, the arthritis resolved without DMARDs in 9/23 patients (39.1%). The corresponding proportion for 2-6 weeks duration was 5/36 (13.9%), and for >6 weeks duration 9/143 (6.3%). The patients with resolved arthritis less often had positive anti-CCP (p<0.001), were less often current daily smokers (p=0.01) and had fewer RA criteria points (p=0.02). There were no significant differences between the groups with regard to sex, age, 68-swollen and 28-tender joint counts, ESR, CRP, BMI, fatigue, joint pain, patient global, assessor global, HAQ or distribution of mono-, oligo- and polyarthritis.
Conclusions Among patients who fulfilled the RA criteria at baseline, the arthritis resolved without initiation of DMARD treatment in a considerable proportion of patients in whom baseline duration of joint swelling was very short. Patients with arthritis of more than 6 weeks duration experienced resolution of arthritis less frequently.
Disclosure of Interest None declared