Clinical and Biomechanical Factors Associated With Falls in Rheumatoid Arthritis

Patients with rheumatoid arthritis (RA) were found to have clinical and biomechanical characteristics associated with fall risk, according to study results published in Rheumatology. Risk factors associated with falls included older age, higher pain and dizziness levels, lower health-related quality of life, and psychotropic medication use. In patients who received gait assessment, biomechanical factors associated with falls included shorter stride length, reduced torque and strength during knee flexion, and greater anteroposterior and medial-lateral sway.

Falls are a major cause of morbidity and mortality among older adults, particularly those with RA. To elucidate the clinical and biomechanical characteristics linked to falls in RA, the researchers conducted a prospective study of patients receiving care at a rheumatology clinic in the United Kingdom.

Eligible participants were aged 60 years and older and had a clinical diagnosis of RA, and were enrolled in the study between 2012 and 2014; each patient was followed up for 1 year from baseline assessment. At baseline, participants completed a survey, which included age, sex, marital and employment status, physical activity, visual analog scale (VAS) pain score, VAS fatigue score, self-reported dizziness experienced, health-related quality of life (according to the EuroQol-5 Dimension), and 12-month history of falls. Participants were followed up every month for 12 months for incident falls, defined as “an unexpected event in which the participant…[came] to rest on the ground, floor, or lower level.”

A nested cohort of participants with and without incident falls received biomechanical assessments of joint range of motion, muscle strength, and gait. Multivariate regression models were used to identify correlates of prior falls; descriptive statistics were used to compare biomechanical characteristics between patients with and without incident falls.

The study cohort included 436 patients with RA, among whom 200 (46%) had a history of falls in the 12-month period prior to study enrollment. Mean age of patients with a history of falls was 73.2±7.9 years; mean age of patients without a history of falls was 71.4±6.8 years. A total of 73% of the participants in the falls group were women compared with 65% in the non-falls group.

Compared with patients without a history of falls, those with a history of falls were older (odds ratio [OR], 1.04; 95% CI, 1.01-1.07; P =.05), more likely to be unmarried (OR, 1.73; 95% CI, 1.06-2.86; P =.03), more likely to report dizziness (OR, 2.46; 95% CI, 1.56-3.91; P <.01), and more likely to be taking psychotropic medications (OR, 1.82; 95% CI, 1.09-3.05; P =.02). Patients with vs without a fall history also had higher mean VAS pain scores (OR, 1.02; 95% CI, 1.01-1.03; P <.01). Fall history was not significantly associated with sex, employment status, home-based physical activity levels, VAS fatigue scores, having a diagnosis of Parkinson disease, prior stroke, or taking 4 or more medications (P >.05).

The nested cohort included 30 patients who experienced falls during follow-up and 30 patients who did not. Median number of falls was 2.00 (interquartile range, 1.00-3.75). Body mass index, employment status, and marital status did not differ between the 2 groups. Substantial biomechanical differences were detected; specifically, patients who experienced falls had significantly higher postural sway and sway range in both the anteroposterior and mediolateral directions (all P <.05). Patients with vs without incident falls also had significantly lower isokinetic peak torque at 60 ° knee flexion (48.23 vs 57.95 Newton-meters [Nm], respectively; P =.03). Patients in the falls vs no-falls group had significantly shorter mean stride length (1.05 vs 1.18 m, respectively; P =.04), longer double support time (0.39 vs 0.32 s, respectively; P =.04), and reduced percentage time in swing (34.2% vs 36.8%, respectively; P =.02). In the falls vs no-falls group, knee range of motion (50.3 ° vs 58.3 °, respectively; P <.01) and knee flexion (51.6 ° vs 56.0 °; P <.01) were also significantly reduced. 

A study limitation included the relatively small number of patients who received biomechanical assessment.

“Characteristic clinical and biomechanical factors have been identified as associated with falls in people with RA,” the researchers wrote. “Our findings suggest that physical activity performance alone may be insufficient to reduce falls, and that targeting interventions to address specific biomechanical deficits for those individuals with RA at increased falls risk, would be appropriate.”

Reference

Smith TO, Clarke C, Dainty JR, et al. Clinical and biomechanical factors associated with falls and rheumatoid arthritis: baseline cohort with longitudinal nested case-control study. Rheumatology (Oxford). Published online April 26, 2021. doi:10.1093/rheumatology/keab388