Monitoring 6-month trajectory of grip strength improves the prediction of long-term change in grip strength in disabled older women

Background: This study aims to assess the degree and heterogeneity of decline in grip strength in the short term (6 months) and the clinical relevance of short-term decline to long-term decline (2.5 years) in grip strength in disabled older women. Methods: Eighty-four community-dwelling disabled women aged 65 years or older were evaluated on a weekly basis over 6 months, followed by an additional five semi-annual visits for a total follow-up of 3 years. The study outcome is maximum isometric handgrip strength in the nondominant hand. Linear random effects models were used to characterize population-as well as individual-level change in grip strength over time. Results: In the weekly assessments over the initial 6 months, individual-level short-term change in grip strength was detectable (mean = -0.12 kg/month; p =.06), heterogeneous (range: -2.03 ± 0.95 kg/month), and independent of absolute grip strength at baseline (mean = 18.4 kg). Additionally, among women with grip strength greater than 16.7 kg at baseline, the long-term rate of decline in grip strength was accelerated by 0.15 kg/year (p =.014) for every 0.5 standard deviation (0.25 kg/month) increase in the short-term rate of decline. The baseline absolute grip strength, however, was not significantly associated with the long-term rate of decline (correlation = -0.36, p =.105). Conclusions: Our findings suggest that short-term change in grip strength is detectable and meaningful for disabled older women and it is the individual's past trajectory of grip strength relative to her current strength level, not her current absolute strength per se, that is important for predicting future strength decline.