Biomechanical and clinical factors associated with recurrent falls in older people with rheumatoid arthritis: a longitudinal cohort with nested case-control study

Objective: To identify the clinical and biomechanical characteristics associated with falls in people with RA. 
Methods: 436 people aged 60 years or older with RA completed a one-year prospective survey of falls in the UK. At baseline, questionnaires recorded data including: personal and medical history, pain and fatigue scores, health related quality of life (HRQoL), physical activity and medication history. Occurrence of falls was monitored prospectively over 12 months by monthly self-reporting. A nested sample of 30 fallers (defined as the report of one or more falls in 12 months) and 30 non-fallers, were evaluated to assess joint range of motion (ROM), muscle strength and gait parameters. Multivariate regression analyses were undertaken to determine variables associated with falling. 
Results: Compared with non-fallers (n=236), fallers (n=200) were older (p=0.05), less likely to be married (p=0.03), had higher pain scores (p<0.01), experienced more frequent dizziness (p<0.01), were frequently taking psychotropic medications (p=0.02) and reported lower HRQoL (p=0.02). Among those who underwent gait laboratory assessments, compared with non-fallers, fallers showed a greater anteroposterior (AP (p=0.03) and medial-lateral (ML) sway range (p=0.02), and reduced isokinetic peak torque and isometric strength at 60° knee flexion (p=0.03). Fallers also showed shorter stride length (p=0.04); shorter double support time (p=0.04); reduced percentage time in swing phase (p=0.02); and in knee ROM through the gait cycle (p<0.01). 
 Conclusion: People with RA have distinct clinical and biomechanical characteristics that place them at increased risk of falling. Assessment for these factors may be important to offer more targeted rehabilitation interventions.