Grip Strength Cutpoints for the Identification of Clinically Relevant Weakness

Abstract

Background.Weakness is common and contributes to disability, but no consensus exists regarding a strength cutpoint to identify persons at high risk. This analysis, conducted as part of the Foundation for the National Institutes of Health Sarcopenia Project, sought to identify cutpoints that distinguish weakness associated with mobility impairment, defined as gait speed less than 0.8 m/s.Methods.In pooled cross-sectional data (9,897 men and 10,950 women), Classification and Regression Tree analysis was used to derive cutpoints for grip strength associated with mobility impairment.Results.In men, a grip strength of 26–32 kg was classified as “intermediate” and less than 26 kg as “weak”; 11% of men were intermediate and 5% were weak. Compared with men with normal strength, odds ratios for mobility impairment were 3.63 (95% CI: 3.01–4.38) and 7.62 (95% CI 6.13–9.49), respectively. In women, a grip strength of 16–20 kg was classified as “intermediate” and less than 16 kg as “weak”; 25% of women were intermediate and 18% were weak. Compared with women with normal strength, odds ratios for mobility impairment were 2.44 (95% CI 2.20–2.71) and 4.42 (95% CI 3.94–4.97), respectively. Weakness based on these cutpoints was associated with mobility impairment across subgroups based on age, body mass index, height, and disease status. Notably, in women, grip strength divided by body mass index provided better fit relative to grip strength alone, but fit was not sufficiently improved to merit different measures by gender and use of a more complex measure.Conclusions.Cutpoints for weakness derived from this large, diverse sample of older adults may be useful to identify populations who may benefit from interventions to improve muscle strength and function.

Clinically relevant weakness in diverse populations of older adults participating in the International Mobility in Aging Study

“…We used Classification Regression Trees (CART), as explained in Alley et al (2014), to identify IMIAS cut points for grip strength associated with slowness. This statistical procedure can identify subgroups of a population whose members share common characteristics that influence the dependent variable of interest (De'ath and fabricius 2000; Lemon et al 2003;Razi and Athappilly 2005).…”

“…The tree was pruned to the most parsimonious model within one standard prediction error of the tree with the smallest prediction error. CART analysis to verify the associations between muscle strength and slowness has been used in previous studies (Hicks et al 2012;Alley et al 2014). We then estimated weighted kappa coefficients to assess the agreement between the FNIH and the IMIAS classifications of clinically relevant weakness.…”

“…Recently, several HGS cut points have been proposed to identify clinically relevant weakness (Zalewski et al 2009;Cruz-Jentoft et al 2010;Sallinen et al 2010;Hicks et al 2012;Seino et al 2014;Alley et al 2014). The Foundation for the National Institutes of Health (FNIH) Sarcopenia Project working group published cut points of handgrip weakness associated with slowness in walking ).…”

“…However, with few exceptions (García-Peña et al 2013;Lourenço et al 2015), all published studies have been carried out on populations living in high-income countries. Globally validated cut points for clinically relevant weakness could provide health professionals an important tool to identify older adults at risk for functional problems (Hicks et al 2012;Alley et al 2014).…”

Grip strength and healthy aging

“…At the threshold point of impaired physical capacity, lower limits are more serious in women. The Foundation for the National Institutes of Health Sarcopenia Project criteria defined grip strength 147 JPFSM : Grip strength and healthy aging of less than 16 kg in women as "weak" 46) . For maintaining mobility, which is the most basic ability for daily living, the grip strength cut-off value for self-reported difficulties was 19 kg in a British cohort 2) and 20 kg (body mass index: 20-24.9 kg/m 2 ) for difficulties in walking (0.5 km) or stair climbing in a Finnish cohort 47) .…”