Measurement of physical capacities in the elderly: a secondary analysis of the Quebec longitudinal study NuAge

OBJECTIVE: To assess the validity of a battery of functional capacity tests in community-living elderly Canadians. MATERIAL AND METHODS: Design: cross-sectional study. Study population: baseline data from 1793 men and women aged 74.4 +/- 4.1 participating in the NuAge longitudinal study were collected from December 2003 to April 2005 and used for the analyses. A global score measuring functional capacities (BFC) was constructed as the sum of four tests according to a method proposed by Guralnik Timed Up and Go, walking speed (4 m), chair stands (five times), standing balance]. Multivariate linear regression analysis was used to study the relationship between age, sex, and physical activity, and BFC score. RESULTS: The global functional capacities score had an internal consistency of 0.74. It was significantly associated with age, sex and measures of mental and physical health status including: cognitive function (< 0.001), depressive symptoms (< 0.001), nutritional risk (< 0.001), burden of disease (< 0.001), and level of physical activity (< 0.001) thus supporting the construct validity of the global score. Age related differences in BFC were consistent and similar among men and women. CONCLUSION: The global score of functional capacity tests provided a valid assessment of physical capacities in the community-living elderly. While men had higher global BFC scores than women, among both sexes the best performance was observed in the youngest age group and in those reporting more physical activity.