Factors associated with time to diagnosis from symptom onset in patients with early rheumatoid arthritis

Background/Aims: To identify the factors associated with time to diagnosis after symptom onset in patients with early rheumatoid arthritis (RA). Methods: Early RA patients with <= 1 year of disease duration in the KORean Observational study Network for Arthritis (KORONA) database were included in this analysis. Patients were further divided into two groups according to the time to diagnosis from symptom onset: the early diagnosis group (time to diagnosis <= 1 year) and the late diagnosis group (time to diagnosis > 1 year). Using the multi-variable regression model, we identified factors associated with early diagnosis. Results: Among 714 early RA patients, 401 patients (56.2%) and 313 patients (43.8%) were included in the early diagnosis and late diagnosis groups, respectively. The mean disease duration was 0.47 years in the early diagnosis group and 0.45 years in the late diagnosis group. In multivariable model analysis, greater age at onset (odds ratio [OR], 1.03; 95% confidence interval [CI], 1.02 to 1.05), high school education or higher (OR, 1.68; 95% CI, 1.14 to 2.47), higher income (OR, 1.48; 95% CI, 1.05 to 2.08), and initial small joint involvement (OR, 1.42; 95% CI, 1.02 to 1.98) were factors associated with early diagnosis. At diagnosis, disease activity scores using 28 joints on diagnosis (3.81 +/- 1.44 vs. 3.82 +/- 1.42, p = 0.92) and functional disability (0.65 +/- 0.61 vs. 0.57 +/- 0.62, p = 0.07) did not different between the two groups. However, hand joint erosion on X-ray (37.8% vs. 25.6%, p < 0.01) was more common in the late diagnosis group than the early diagnosis group. Conclusions: Older onset age, higher educational level and income, and initial small joint involvement were positive factors for early diagnosis of RA.