Walking speed as a good predictor for the onset of functional dependence in a Japanese rural community population.

OBJECTIVE: to investigate and compare the predictive values of four physical performance measures for the onset of functional dependence in older Japanese people living at home.
DESIGN: a population-based prospective cohort study.
SETTING: Nangai village, Akita Prefecture, Japan.
METHODS: out of the population aged 65 years and older living in Nangai (n = 940) in 1992, we measured hand grip-strength, one-leg standing, and usual and maximum walking speeds in 736 subjects who were independent in the five basic activities of daily living. Their functional status was assessed each year for the subsequent 6 years. The outcome event was the onset of functional dependence, defined as a new disability in one or more of the five basic activities of daily living, or death of a subject who had shown no disability at the previous follow-up.
RESULTS: even after controlling for age, sex and a number of chronic conditions, lower scores on each baseline performance measure showed increased risk for the onset of functional dependence. Maximum walking speed was most sensitive in predicting future dependence for those aged 65-74 years, while usual walking speed was most sensitive for people aged > or = 75 years.
CONCLUSION: walking speed was the best physical performance measure for predicting the onset of functional dependence in a Japanese rural older population.