Disability Related to Function of the Upper Extremities in Early Rheumatoid Arthritis – Course and Relation to Other Disease Parameters Over 10 Years: A Cohort Study

Background: The objective of this study was to investigate the course of disability related to the upper extremities (UE) in early rheumatoid arthritis (RA), and to assess correlations between such disability and clinical parameters, including grip force. Methods: In an inception cohort of patients with early RA (N=222), disability of the UE was assessed using a subscore of the Health assessment questionnaire disability index (HAQ-DI), and average grip force of the dominant hand was measured. Changes between consecutive follow-up visits in the HAQ-DI-UE subscore were assessed using the paired samples t-test, and correlations with key disease parameters using Spearman’s rank test. The relation between joint involvement and HAQ-DI-UE was examined using multivariate linear regression analysis. Results: The HAQ-DI-UE decreased significantly from inclusion to the 6-month follow-up (mean change -0.26; 95% CI -0.18 to -0.34), and increased significantly after 2 years. There were fairly strong correlations for HAQ-DI-UE with grip force (r: -0.50 to -0.62), patient’s global assessment (r:0.58 to 0.64) and patient’s assessment of pain (r:0.54 to 0.60) at all time points up to 5 years, but only moderate to weak correlations with swollen joints, CRP and ESR. At inclusion wrist synovitis and tender PIP joints had both an independent impact on HAQ-DI-UE, whereas tenderness of the shoulder and the wrist had a greater importance at 6 months. Conclusions: Disability related to the upper extremities decreased significantly during the first 6 months, and increased again after 2 years. The correlations with clinical parameters underline the major impact of pain and impaired hand function in early RA.