Brief Report: Predicting Functional Disability: One-Year Results From the Scottish Early Rheumatoid Arthritis Inception Cohort

Abstract

Objective: To identify baseline prognostic indicators of disability at 1 year within a contemporary early inflammatory arthritis inception cohort and then develop a clinically useful tool to support early patient education and decision-making. Methods: The Scottish Early Rheumatoid Arthritis (SERA) inception cohort is a multicenter, prospective study of patients with newly presenting RA or undifferentiated arthritis. SERA data were analyzed to determine baseline predictors of disability (defined as a Health Assessment Questionnaire [HAQ] score of ≥1) at 1 year. Clinical and psychosocial baseline exposures were entered into a forward stepwise logistic regression model. The model was externally validated using newly accrued SERA data and subsequently converted into a prediction tool. Results: Of the 578 participants (64.5% female), 36.7% (n = 212) reported functional disability at 1 year. Functional disability was independently predicted by baseline disability (odds ratio [OR] 2.67 [95% confidence interval (95% CI) 1.98, 3.59]), depression (OR 2.52 [95% CI 1.18, 5.37]), anxiety (OR 2.37 [95% CI 1.33, 4.21]), being in paid employment with absenteeism during the last week (OR 1.19 [95% CI 0.63, 2.23]), not being in paid employment (OR 2.36 [95% CI 1.38, 4.03]), and being overweight (OR 1.61 [95% CI 1.04, 2.50]). External validation (using 113 newly acquired patients) evidenced good discriminative performance with a C statistic of 0.74, and the calibration slope showed no evidence of model overfit (P = 0.31). Conclusion: In the context of modern early inflammatory arthritis treatment paradigms, predictors of disability at 1 year appear to be dominated by psychosocial rather than more traditional clinical measures. This indicates the potential benefit of early access to nonpharmacologic interventions targeting key psychosocial factors, such as mental health and work disability.