Abstract
BACKGROUND: Neuromuscular and clinical factors contribute to falls among older adults, yet the interrelated nature of these factors is not well understood. We investigated the relationships between these factors and how they contribute to falls, which may help optimize fall risk assessment and prevention. METHODS: A total of 365 primary care patients (age = 77 ± 7, 67% female) were included from the Boston Rehabilitative Impairment Study of the Elderly. Neuromuscular measures included leg strength and leg velocity, trunk extensor endurance, and knee range of motion. Clinical measures included memory, executive function, depressive symptoms, pain, sensory loss, vision, comorbidity, physical activity, mobility self-efficacy, and psychiatric medication. Factor analysis was used to evaluate clustering of factors. Negative binomial regression assessed the relationship of factors with three-year fall rate. Interactions were tested to examine whether clinical factors modified the relationship between neuromuscular factors and falls. RESULTS: Three factors emerged: (i) neuromuscular factors, pain, and self-efficacy; (ii) memory; and (iii) executive function. Having three neuromuscular impairments predicted higher fall rate (incidence rate ratio [95% confidence interval]: 3.39 [1.82-6.32]) but was attenuated by memory (1.69 [1.10-2.61]), mobility self-efficacy (0.99 [0.98-0.99]), psychiatric medication use (1.54 [1.10-2.14]), and pain (1.13 [1.04-1.23]). Pain modified the relationship between neuromuscular impairment burden (number of neuromuscular impairments) and falls. Having three neuromuscular impairments was associated with a higher fall rate in patients with high levels of pain (5.73 [2.46-13.34]) but not among those with low pain. CONCLUSIONS: Neuromuscular impairment burden was strongly associated with fall rate in older adults with pain. These factors should be considered together during fall risk assessment, post fall assessment, and prevention.