Background One of the serious consequences of aging is the gradual loss of muscle function, a phenomenon called sarcopenia. Skeletal muscle power refers to the ability to generate high-velocity movements and current evidence suggests that it declines earlier with advancing age [1] and is more strongly related to functional status than muscle force [2]. A decreased capacity for high-velocity movements in the legs has been linked to delayed responses in maintaining postural stability and thus with age-associated fall risk [3]. People with rheumatoid arthritis (RA) may be at high risk of falling due to disease-related impairments such as pain, joint deformity, muscle weakness, altered gait and decline in postural stability.

Objectives As role of muscle power in fall-risk assessment of RA patients has not been investigated, so far, the aim of the present study was to determine the association between muscle power, muscle force, functional performance and falls in the last 12 months in RA patients.

Methods 98 subjects with RA older than 60 years from a cross-sectional study on the prevalence of corticoid-induced osteoporosis in Germany (PSIO-D Berlin) and 98 age-matched controls without inflammatory disease, randomly chosen from a cross-sectional study collecting reference values for body composition, were analyzed in this case-control study. Muscle function was determined by muscle power per body mass in vertical countermovement jumps (2LJP_rel) on a force plate, the chair rise test (CRT), gait speed, grip strength and the Short Physical Performance Battery. Differences in muscle function measures between the RA group and the healthy reference were derived separately by sex with Student-T-test or Mann-Whitney-U-test. Using logistic regression adjusted for age and sex the association between muscle function and falls was determined.

Results In bivariate analysis RA patients showed significantly weaker performance in all muscle function tests compared to controls in both sexes. Applying logistic regression, age (OR 1.10, 95%>CI 1.00–1.24) and female sex (OR 5.99, 95%>CI 1.25–28.57) were significantly associated with retrospective falls in RA subjects but not in controls. Gait speed (OR 0.09, 95%>CI 0.01–0.88) remained a significant correlate for falls independent of age and sex in RA patients. In controls only the CRT (OR 1.13, 95%>CI 1.02–1.26) could differentiate individuals who had past fall events in the age and sex adjusted model. No association was found for the 2LJP_rel and retrospective falls.

Conclusions The results of the present study could not confirm an association between fall risk and muscle power in RA patients, but they highlight the importance of monitoring neuromuscular function such as gait speed, in order to prevent falls and consequently to prevent fractures, contributing to a better prognosis of rheumatic disease.

References

1. Lauretani, F., et al., Age-associated changes in skeletal muscles and their effect on mobility: an operational diagnosis of sarcopenia. J Appl Physiol, 2003. 95(5): p. 1851–60.

2. Bean, J.F., et al., A comparison of leg power and leg strength within the InCHIANTI study: which influences mobility more? J Gerontol A Biol Sci Med Sci, 2003. 58(8): p. 728–33.

3. Pereira, A., et al., Effects of high-speed power training on functional capacity and muscle performance in older women. Exp Gerontol, 2012. 47(3): p. 250–5.

References

Disclosure of Interest None declared