Impact of early diagnosis on functional disability in rheumatoid arthritis

Background/Aims: To determine whether early diagnosis is beneficial for functional status of various disease durations in rheumatoid arthritis (RA) patients. Methods: A total of 4,540 RA patients were enrolled as part of the Korean Observational Study Network for Arthritis (KORONA). We defined early diagnosis as a lag time between symptom onset and RA diagnosis of ${\leq}12$ months, whereas patients with a longer lag time comprised the delayed diagnosis group. Demographic characteristics and outcomes were compared between early and delayed diagnosis groups. Logistic regression analyses were performed to identify the impact of early diagnosis on the development of functional disability in RA patients. Results: A total of 2,597 patients (57.2%) were included in the early diagnosis group. The average Health Assessment Questionnaire-Disability Index (HAQ-DI) score was higher in the delayed diagnosis group ($0.64{\pm}0.63$ vs. $0.70{\pm}0.66$, p < 0.01), and the proportion of patients with no functional disability (HAQ = 0) was higher in the early diagnosis group (22.9% vs. 20.0%, p = 0.02). In multivariable analyses, early diagnosis was independently associated with no functional disability (odds ratio [OR], 1.19; 95% confidence interval [CI], 1.01 to 1.40). In a subgroup analysis according to disease duration, early diagnosis was associated with no functional disability in patients with disease duration < 5 years (OR, 1.37; 95% CI, 1.09 to 1.72) but not in patients with longer disease duration (for 5 to 10 years: OR, 1.07; 95% CI, 0.75 to 1.52; for ${\geq}10$ years: OR, 0.92; 95% CI, 0.65 to 1.28). Conclusions: Early diagnosis is associated with no functional disability, especially in patients with shorter disease duration.