Investigating the predictive ability of gait speed and quadriceps strength for incident falls in community-dwelling older women at high risk of fracture

Abstract

Gait speed is a recommended geriatric assessment of physical performance, but may not be regularly examined in clinical settings. We aimed to investigate whether quadriceps strength tests demonstrate similar predictive ability for incident falls as gait speed in older women. We investigated 135 female volunteers aged mean ± SD 76.7 ± 5.0 years (range 70–92) at high risk of fracture. Participants completed gait speed assessments using the GAITRite Electronic Walkway System, and quadriceps strength assessments using a hand-held dynamometer (HHD). Participants reported incident falls monthly for 3.7 ± 1.2 years. N = 99 (73%) participants fell 355 times during the follow-up period (mean fall rate 83 per 100 person years). We observed a reduced odds ratio for multiple falls (0.83, 95% CI 0.70–0.98) and a reduced hazard ratio for time to first fall (0.90, 95% CI 0.83–0.98), according to quadriceps strength. There was also a significantly shorter time to first fall for those with low quadriceps strength (<7.0 kg; lowest tertile) compared with those with normal quadriceps strength (estimated means [95% CI] 1.54 [1.02, 2.06] vs. 2.23 [1.82, 2.64] years; P = 0.019), but not for those with low (<1.0 m/s) vs. normal gait speed (P = 0.15). Quadriceps strength is a significant predictor of incident falls over three years amongst community-dwelling older women at high risk of fracture. Quadriceps strength tests may be an acceptable alternative to gait speed for geriatric assessments of falls risk.

Introduction

In older adults, low gait speed predicts adverse events including incident mobility limitations, disability, hospitalization, loss of independence and falls (Cesari et al., 2005, Fried et al., 2000, Guralnik et al., 2000, Montero-Odasso et al., 2005). This has led to recommendations for the assessment of gait speed in the clinical setting to identify older patients at risk of functional decline (Abellan Van Kan et al., 2009) and those with sarcopenia. Both the European Working Group on Sarcopenia in Older People (EWGSOP) and International Working Group on Sarcopenia (IWG) have recently developed consensus definitions of sarcopenia (Cruz-Jentoft et al., 2010, Fielding et al., 2011) which include an assessment of gait speed. The EWGSOP classify sarcopenia as low gait speed (<0.8 m/s) or low grip strength in combination with low muscle mass (Cruz-Jentoft et al., 2010), while the IWG classify sarcopenia as low gait speed (<1.0 m/s) in combination with low muscle mass (Fielding et al., 2011). These algorithms have been formulated in an effort to increase the previously poor attention to sarcopenia by providing practitioners with standardized diagnostic criteria for sarcopenia (Janssen, 2011).

Sarcopenia is an independent risk factor for falls and so clinicians may utilize sarcopenia algorithms in falls risk stratification processes (Landi et al., 2012). However, there is controversy associated with the assessment of gait speed in an operational definition of sarcopenia. Gait speed is not an assessment of muscle function alone, given that it is influenced by other parameters including neurological factors and cardiovascular fitness (Bijlsma et al., 2012), and Morley has noted that the use of gait speed to diagnose sarcopenia results in overlap with definitions of frailty (Morley, 2012). Furthermore, despite the relative simplicity with which gait speed can be assessed (Studenski et al., 2011), practitioners may hold perceptions that such measurements require substantial space, equipment and time to complete (Cesari et al., 2005).

Assessments of quadriceps strength are common in research settings and quadriceps strength is an independent predictor of incident falls, fractures and mortality in older adults (Lord et al., 1994, Newman et al., 2006, Nguyen et al., 2005). These tests may also be more easily performed than gait speed assessments in the clinical setting, as they require less time and space, and can be performed with the patient sitting or lying down. As a result, quadriceps strength tests may be an appropriate substitute for gait speed assessments for clinicians attempting to identify patients at risk of incident functional declines. The aim of this study was to investigate whether quadriceps strength tests demonstrate similar predictive ability for incident falls as gait speed in older women.